A350964 a(n) is the largest prime factor of 2^p - p^2 where p is the n-th prime.
7, 79, 47, 113, 130783, 523927, 1198297, 240641, 641, 575058377, 1519711993, 65929327, 20105355479017, 9007199254738183, 7633399, 33189241, 21081993227096629777, 951850902549409, 4978773308244222679, 501615233613780359, 9671406556917033397642519, 8251206137, 3818597055399121, 13314319257913, 521211122055087383048446607
Offset: 3
Keywords
References
- E.-B. Escott, Note #1642, L'Intermédiaire des Mathématiciens, 8 (1901), page 12.
Links
- Amiram Eldar, Table of n, a(n) for n = 3..95
- Robert G. Wilson v, Factorization of 2^p - p^2 for n = 3..120
Programs
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Maple
a:= n-> max(numtheory[factorset]((p-> 2^p-p^2)(ithprime(n)))): seq(a(n), n=3..27); # Alois P. Heinz, Mar 03 2022
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Mathematica
a[n_] := FactorInteger[2^(p = Prime[n]) - p^2][[-1, 1]]; Array[a, 25, 3] (* Amiram Eldar, Mar 03 2022 *)
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PARI
a(n) = my(p=prime(n)); vecmax(factor(2^p - p^2)[,1]); \\ Michel Marcus, Mar 03 2022
Comments