A242084 5^p - 4^p - 1, where p is prime.

8, 60, 2100, 61740, 44633820, 1153594260, 745759583940, 18798608421180, 11850560210900460, 185976284546943991380, 4652001187058965190220, 72740686675902780452348340, 45469899385367953379053128420

Offset

1,1

Comments

For p>3 all terms are divisible by 21.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..100

Formula

a(n) = A054401(A000040(n)). - Michel Marcus, May 05 2014

Mathematica

Table[5^Prime[n] - 4^Prime[n] - 1, {n, 1, 60}]

Prog

(Magma) [5^p-4^p-1: p in PrimesUpTo(60)];
(PARI) a(n) = my(p = prime(n)); 5^p - 4^p - 1; \\ Michel Marcus, May 05 2014

Crossrefs

Cf. A204768.

Sequence in context: A356598 A075147 A034664 * A007399 A071401 A247535

Adjacent sequences: A242081 A242082 A242083 * A242085 A242086 A242087

Keyword

nonn,less

Author

Vincenzo Librandi, May 04 2014

Status

approved