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A227697 Numbers of the form ((p^2 + q^2)/2 - 1)/4, where p and q are odd primes. 1
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 (list; graph; refs; listen; history; text; internal format)
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 A259983

Adjacent sequences:  A227694 A227695 A227696 * A227698 A227699 A227700

KEYWORD

nonn

AUTHOR

Richard R. Forberg, Sep 22 2013

STATUS

approved

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Last modified August 11 23:45 EDT 2020. Contains 336434 sequences. (Running on oeis4.)