OFFSET
1,1
COMMENTS
Subsequence of A156592.
Apparently, a(n) == 1 (mod 36) for n >= 2. - Hugo Pfoertner, Nov 03 2023
EXAMPLE
MATHEMATICA
Select[Accumulate[Range[4500]], (f = FactorInteger[#])[[;; , 2]] == {1, 1} && Mod[f[[;; , 1]], 4] == {3, 3} &] (* Amiram Eldar, Oct 11 2023 *)
PROG
(Magma) pd:=PrimeDivisors; blum:=func<n|#Divisors(n) eq 4 and #pd(n) eq 2 and pd(n)[1] mod 4 eq 3 and pd(n)[2] mod 4 eq 3>; [n:n in [1..9000000]|IsSquare(8*n+1) and blum(n)];
CROSSREFS
KEYWORD
nonn
AUTHOR
Marius A. Burtea, Oct 09 2023
STATUS
approved