A176845 Numbers k such that A147846(k) + A147846(k+1) is a square.

1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 13, 14, 16, 18, 19, 20, 22, 24, 25, 26, 28, 30, 32, 33, 34, 36, 38, 39, 40, 42, 44, 46, 48, 50, 51, 52, 54, 55, 56, 58, 60, 62, 64, 65, 66, 68, 69, 70, 72, 74, 76, 78, 80, 81, 82, 84, 85, 86, 88, 89, 90, 92, 94, 96, 97, 98, 100, 102, 103, 104, 106

Offset

1,2

Comments

Does the sequence contain all even numbers? - Giovanni Teofilatto, Apr 29 2010

Links

Table of n, a(n) for n=1..71.

Maple

From R. J. Mathar, Apr 30 2010: (Start)
A127949 := proc(n) if issqr(1+8*n) then (sqrt(1+8*n)-1)/2 ; else -1 ; end if; end proc:
A147846 := proc(n) option remember ; local k, a ; if n = 1 then 1; else for a from procname(n-1)+1 do k := A127949(a) ; if k > 0 then if isprime(k) or isprime(k+1) then return a; end if; end if; end do; end if; end proc:
isA176845 := proc(n) issqr( A147846(n)+A147846(n+1)) ; end proc:
for n from 1 to 400 do if isA176845(n) then printf("%d, ", n) ; end if; end do; (End)

Crossrefs

Cf. A147846.

Sequence in context: A039162 A328216 A071959 * A196127 A194467 A225857

Adjacent sequences: A176842 A176843 A176844 * A176846 A176847 A176848

Keyword

nonn

Author

Giovanni Teofilatto, Apr 27 2010

Extensions

Corrected (7 replaced by 8) and extended by R. J. Mathar, Apr 30 2010

Status

approved