A227697 Numbers of the form ((p^2 + q^2)/2 - 1)/4, where p and q are odd primes.

2, 4, 6, 7, 9, 12, 16, 18, 21, 22, 24, 27, 30, 36, 37, 39, 42, 46, 48, 51, 57, 60, 66, 67, 69, 72, 81, 87, 90, 102, 106, 108, 111, 120, 121, 123, 126, 132, 135, 141, 150, 156, 165, 171, 172, 174, 177, 186, 192, 207, 210

Offset

1,1

Comments

a(n) mod 3 = 0 if neither prime = 3.

a(n) mod 3 = 1 if one prime = 3.

a(1) mod 3 = 2 (where both primes = 3).

Links

Table of n, a(n) for n=1..51.

Formula

a(n) = (A143850(n)-1)/4.

Crossrefs

Sequence in context: A141437 A219645 A186708 * A097457 A321612 A121865

Adjacent sequences: A227694 A227695 A227696 * A227698 A227699 A227700

Keyword

nonn

Author

Richard R. Forberg, Sep 22 2013

Status

approved