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%I #11 Feb 06 2019 02:30:38
%S 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,
%T 36,38,39,40,42,44,46,48,50,51,52,54,55,56,58,60,62,64,65,66,68,69,70,
%U 72,74,76,78,80,81,82,84,85,86,88,89,90,92,94,96,97,98,100,102,103,104,106
%N Numbers k such that A147846(k) + A147846(k+1) is a square.
%C Does the sequence contain all even numbers? - _Giovanni Teofilatto_, Apr 29 2010
%p From _R. J. Mathar_, Apr 30 2010: (Start)
%p A127949 := proc(n) if issqr(1+8*n) then (sqrt(1+8*n)-1)/2 ; else -1 ; end if; end proc:
%p 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:
%p isA176845 := proc(n) issqr( A147846(n)+A147846(n+1)) ; end proc:
%p for n from 1 to 400 do if isA176845(n) then printf("%d,",n) ; end if; end do; (End)
%Y Cf. A147846.
%K nonn
%O 1,2
%A _Giovanni Teofilatto_, Apr 27 2010
%E Corrected (7 replaced by 8) and extended by _R. J. Mathar_, Apr 30 2010
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