A129446 Primes p such that p^2 is a centered triangular number; or primes in A129445.

2, 19, 79, 1861, 7741, 1647522841025041

Offset

1,1

Comments

The next terms are too large to include, see the b-file.

Links

Alexander Adamchuk, Apr 26 2007, Table of n, a(n) for n = 1..9

Mathematica

Do[ f = 3n(n-1)/2 + 1; If[ PrimeQ[ Sqrt[f] ], Print[ Sqrt[f] ] ], {n, 1, 150000} ]
Select[LinearRecurrence[{0, 10, 0, -1}, {1, 2, 8, 19}, 100], PrimeQ] (* Harvey P. Dale, May 12 2026 *)

Crossrefs

Cf. A005448 (centered triangular numbers).

Cf. A129444 (numbers k such that centered triangular number A005448(k) = 3*k*(k-1)/2 + 1 is a perfect square).

Cf. A129445 (numbers k > 0 such that k^2 is a centered triangular number).

Sequence in context: A317274 A226019 A057326 * A240280 A327820 A331898

Adjacent sequences: A129443 A129444 A129445 * A129447 A129448 A129449

Keyword

nonn

Author

Alexander Adamchuk, Apr 15 2007, Apr 26 2007

Status

approved