A176796 Numbers k such that A129307(k) + A129307(k+1) is a square.

1, 3, 12, 14, 17, 25, 30, 35, 39, 69, 71, 74, 80, 83, 88, 102, 107, 122, 126, 129, 134, 151, 170, 172, 176, 184, 187, 202, 220, 239, 244, 249, 258, 261, 263, 272, 280, 283, 289, 298, 308, 321, 363, 371, 377, 386, 390, 403, 421, 432, 438, 447, 451, 453, 477, 480

Offset: 1

Author

Giovanni Teofilatto, Apr 26 2010

Keywords

• nonn

Comments

Squares are in A075577.

Crossrefs

Cf. A000217, A027861, A075577, A129307.

Programs

Maple

A027861 := proc(n) option remember; local a; if n= 1 then 1; else for a from procname(n-1)+1 do if isprime(a^2+(a+1)^2) then return a; end if; end do: end if; end proc:
A129307 := proc(n) A000217(A027861(n)) ; end proc:
A176796 := proc(n) option remember; if n = 1 then 1; else for a from procname(n-1)+1 do if issqr(A129307(a)+A129307(a+1)) then return a; end if; end do: end if; end proc:
seq(A176796(n),n=1..80) ; # R. J. Mathar, Jun 28 2010

Extensions

Extended beyond a(5) by R. J. Mathar, Jun 28 2010