A227480 Triangular numbers of the form p^2 - 1 where p is a prime.

3, 120, 528, 139128, 160554240, 812293020528, 379188080252621270252095320, 2816640597719456759751165488439681098364673273236637971046370174350128

Offset

1,1

Links

Table of n, a(n) for n=1..8.

Example

139128 is both 527*528/2 and 373^2 - 1 (and 373 is prime).

Mathematica

Select[Prime[Range[100000]]^2-1, OddQ[Sqrt[8#+1]]&] (* The program generates the first six terms of the sequence. *) (* Harvey P. Dale, Sep 17 2023 *)

Crossrefs

Subsequence of A006454 and of A225115.

Sequence in context: A305364 A304956 A316638 * A304694 A316445 A316127

Adjacent sequences: A227477 A227478 A227479 * A227481 A227482 A227483

Keyword

nonn

Author

Shreevatsa R, Jul 12 2013

Extensions

a(7)-a(8) from Giovanni Resta, Jul 13 2013

Status

approved