factordbrpc · fdb
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Largest prime factor · largest prime² + 2 of 61 length 20 Not fully computed yet - the last known term is composite. ↓ .elf file
Show sequence-development graph
Term size (digits) across the sequence
How the sequence develops - decimal digits of each term vs iteration.
nStatus DigitsTermFactorization
0 Fully factored 2 61 61
1 Fully factored 4 3723 3×17×73
2 Fully factored 4 5331 3×1777
3 Fully factored 7 3157731 33×116953
4 Fully factored 11 13678004211<11> 3×17×4649×57689
5 Fully factored 10 3328020723<10> 3×1109340241<10>
6 Fully factored 19 1230635770…83<19> 3×4102119234…61<18>
7 Fully factored 36 1682738221…23<36> 32×28747363×4999036873<10>×1301037147…53<18>
8 Fully factored 35 1692697658…11<35> 32×172×19×457×2140047124…97<13>×3502239997…61<15>
9 Fully factored 30 1226568500…23<30> 32×486764107×2799824122…21<20>
10 Fully factored 39 7839015119…43<39> 3×52163×181548609233<12>×2759210032…39<23>
11 Fully factored 45 7613240002…23<45> 32×11×19×83×4876437169…01<40>
12 Fully factored 80 2377963947…03<80> 32×11×19×73×17312149009<11>×198190072547<12>×1064439275…59<22>×4741762975…83<32>
13 Fully factored 64 2248431612…91<64> 3×683×6506941009<10>×3875851946…31<16>×4351046008…21<35>
14 Fully factored 70 1893160137…43<70> 3×369861284633<12>×3907930129…61<16>×4365966836…37<42>
15 Fully factored 84 1906166641…71<84> 3×17×192×131×3136321985…47<20>×2247672297…59<21>×1121136665…47<38>
16 Fully factored 75 1256947422…11<75> 3×1676840697…93<16>×2498642088…09<59>
17 Fully factored 117 6243212287…83<117> 3×2081070762…61<117>
18 Fully factored 233 4330855518…23<233> 32×137×2657×61211×134153×5110801×10165681×64922171×4772772329…51<195>
19 Composite 390 2277935571…03<390> 3×43×73×1579×5843×2621868160…47<379>
↳ Open Open - the last known term is composite and not yet fully factored.
Open end - submit a factor of the remaining composite (379 digits) of term #19:
2621868160877378825126579075136382046360208966975753418030056977944480770589711699832794047655224211032851683644983511673916177860212167947455514055272305647633705241617675991505380915638749878004220253771259964990215476402459746289809313607845822745032160147208412957079667791722417120783064288829198555410848837326368059582510263700315598364207195231140793215125926959710823747
Check for factors - let the server run a small P-1 / P+1 / ECM step on the composite:
Too large (379 digits; the check runs up to 300).
From the command linefdb · curl
fdb
fdb seq view '61' --type 23 --part last20
curl
curl -s 'https://factordb.com:4059/rpc' -H 'Content-Type: application/json' -d '{"jsonrpc":"2.0","id":1,"method":"sequence_view","params":{"start":{"expr":"61"},"type":23,"part":"last20","fr":0}}'