A073844 a(1) = 1, a(n) = largest prime divisor of A057137(n).

1, 3, 41, 617, 823, 643, 9721, 14593, 3803, 3803, 14405693, 10288065751, 116216501, 12079920647, 7552031, 435503, 1763668414462081, 106377431, 27961, 27961, 205126079, 84225392753, 7347135846537257, 437274720469, 12792129877, 244251294564157

Offset: 1

Author

Jason Earls, Sep 02 2002

Keywords

• nonn

Links

• Daniel Suteu, Table of n, a(n) for n = 1..167

Crossrefs

Cf. A006530, A057137.

Programs

PARI

a(n) = if(n==1, 1, vecmax(factor(sum(i=1, n, i%10*10^(n-i)))[,1])); \\ Daniel Suteu, May 25 2022

Formula

a(n) = A006530(A057137(n)). - Michel Marcus, May 26 2022