A304441 Numbers k such that 8k, 8k+1 and 8k+2 are the sum of two squares; A082982 / 8.

0, 1, 2, 9, 10, 18, 29, 36, 45, 65, 72, 73, 100, 101, 136, 137, 144, 153, 164, 200, 208, 218, 225, 234, 245, 281, 288, 289, 298, 324, 325, 353, 416, 424, 441, 450, 514, 522, 541, 578, 640, 648, 666, 676, 738, 757

Offset: 1

Author

M. F. Hasler, May 13 2018

Keywords

• nonn

Comments

Numbers n such that n and n+1 are in the sequence: 0, 1, 9, 72, 100, 136, 288, 324, ...: appear to be in A155562, A140612, and A243180, and in A020684 (except for 1), A034024 & A135571 (except for 0, 1).

Crossrefs

Cf. A082982, A155562, A243180, A140612, A020684, A034024, A135571.

Programs

PARI

isA001481(n)=my(f=factor(n)); for(i=1, #f[, 1], if(f[i, 2]%2 && f[i, 1]%4==3, return(0))); 1
is(n)=isA001481(n) && isA001481(8*n+1) && isA001481(8*n+2) \\ Charles R Greathouse IV, May 17 2018

Formula

a(n) = A082982(n) / 8.