A155577 Intersection of A154777 and A154778: N = a^2 + 2b^2 = c^2 + 5d^2 for some positive integers a,b,c,d.

6, 9, 24, 36, 41, 54, 81, 86, 89, 96, 129, 134, 144, 150, 164, 166, 201, 214, 216, 225, 241, 246, 249, 281, 294, 321, 324, 326, 344, 356, 369, 384, 401, 409, 441, 449, 454, 486, 489, 516, 521, 534, 536, 566, 569, 576, 600, 601, 614, 641, 656, 664, 681, 694

Offset

1,1

Comments

Subsequence of A155567 (where a,b,c,d may be zero).

Links

Table of n, a(n) for n=1..54.

Prog

(PARI) isA155577(n, /* optional 2nd arg allows us to get other sequences */c=[5, 2]) = { for(i=1, #c, for(b=1, sqrtint((n-1)\c[i]), issquare(n-c[i]*b^2) & next(2)); return); 1}
for( n=1, 999, isA155577(n) & print1(n", "))

Crossrefs

Cf. A000404, A154777, A092572, A097268, A154778, A155716, ...

Sequence in context: A295726 A034718 A215528 * A084431 A176498 A142877

Adjacent sequences: A155574 A155575 A155576 * A155578 A155579 A155580

Keyword

easy,nonn

Author

M. F. Hasler, Jan 25 2009

Status

approved