A145837 Indices of primes in A005891(n).

3, 8, 11, 15, 20, 23, 36, 44, 47, 48, 60, 68, 71, 75, 83, 84, 87, 92, 111, 116, 128, 132, 143, 144, 156, 159, 164, 167, 168, 183, 192, 200, 204, 207, 215, 224, 228, 231, 236, 239, 264, 272, 287, 299, 300, 303, 312, 315, 320, 323, 356, 359, 360, 363, 372, 387

Offset: 1

Author

Alexander Adamchuk, Mar 21 2009

Keywords

• nonn

Comments

Corresponding centered pentagonal primes are listed in A145838 = {31, 181, 331, 601, 1051, 1381, 3331, ...}.

Links

• Eric Weisstein's World of Mathematics, Centered Pentagonal Number

Crossrefs

Cf. A145838 = Primes in A005891. Cf. A005891 = Centered pentagonal numbers: (5n^2+5n+2)/2.

Programs

Mathematica

(Position[LinearRecurrence[{3,-3,1},{1,6,16},400], ?PrimeQ]// Flatten)-1 (* _Harvey P. Dale, Sep 08 2018 *)

Formula

A005891(a(n)) = A145838(n)

Extensions

Extended by R. J. Mathar, Mar 26 2009

Edited by N. J. A. Sloane, Apr 06 2009