A091277 Numbers k such that the k-th prime is of the form m^2 + (m+1)^2.

3, 6, 13, 18, 30, 42, 65, 82, 112, 135, 170, 197, 212, 271, 284, 319, 353, 369, 445, 505, 612, 682, 933, 1069, 1193, 1226, 1286, 1510, 1609, 1676, 1711, 1789, 1900, 2161, 2241, 2285, 2363, 2450, 2667, 2712, 2924, 3247, 3644, 3894, 4000, 4100, 4367, 4647, 4922

Offset: 1

Author

Ray Chandler, Jan 03 2004

Keywords

• nonn
• easy

Comments

Also, the k-th prime is of the form (m^2+1)/2.

Links

• Jinyuan Wang, Table of n, a(n) for n = 1..1000 (terms 1..500 from Harvey P. Dale)

Crossrefs

A027862 indexed by A000040.

Cf. A002731, A027861, A027862.

Programs

Mathematica

Select[Range[5000],OddQ[Sqrt[2Prime[#]-1]]&] (* Harvey P. Dale, Jun 25 2018 *)

Formula

a(n)=k such that A000040(k)=A027862(n).

Extensions

Offset changed to 1 by Jinyuan Wang, Aug 02 2021