A263413 Largest prime (or noncomposite) factor of the Crandall number A262961(n).

0, 1, 2, 5, 151, 661, 521, 49993, 858868651, 115523, 72920757563, 3844109, 1637177, 7158605959, 17024617, 13062611, 66113257898351335849, 599880481206897379, 745125370039, 4314028165895642655831229, 30699710580827, 1744795596758086587163381, 2463356705098399667815003

Offset: 1

Author

M. F. Hasler, Oct 17 2015

Keywords

• nonn
• hard

Comments

Computed up to n = 94 by David Broadhurst, and independently up to n = 67 by Hans Havermann and M. F. Hasler.

At n = 95 and n = 96 we have composite factors of 157 digits with probably no divisor less than 50 digits. - David Broadhurst, Oct 17 2015

Links

• David Broadhurst, Table of n, a(n) for n = 1..94
• Hans Havermann and David Broadhurst, Crandall Numbers Factored

Crossrefs

Cf. A262961.

Programs

PARI

a(n)=A006530(A262961(n)) \\ M. F. Hasler, Oct 17 2015

Formula

a(n) = A006530(A262961(n)).