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A097269 Numbers that are the sum of two nonzero squares but not the difference of two nonzero squares. 14
2, 10, 18, 26, 34, 50, 58, 74, 82, 90, 98, 106, 122, 130, 146, 162, 170, 178, 194, 202, 218, 226, 234, 242, 250, 274, 290, 298, 306, 314, 338, 346, 362, 370, 386, 394, 410, 442, 450, 458, 466, 482, 490, 514, 522, 530, 538, 554, 562, 578, 586, 610, 626, 634 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Intersection of A000404 (sum of squares) and complement of A024352 (difference of squares).

Numbers of the form 4k+2 = double of an odd number, with the odd number equal to the sum of 2 squares (sequence A057653). - Jean-Christophe Hervé, Oct 24 2015

Numbers that are the sum of two odd squares. - Jean-Christophe Hervé, Oct 25 2015

LINKS

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

Eric Weisstein's World of Mathematics, Sum of Squares Function.

EXAMPLE

2 = 1^2 + 1^2, 10 = 1^2 + 3^2, 18 = 3^2 + 3^2.

PROG

(PARI) is(n)=if(n%4!=2, return(0)); my(f=factor(n/2)); for(i=1, #f[, 1], if(bitand(f[i, 2], 1)==1&&bitand(f[i, 1], 3)==3, return(0))); 1 \\ Charles R Greathouse IV, May 31 2013

CROSSREFS

Cf. A000404, A024352, A097268, A097270, A097271. Equals twice A057653.

Cf. A020668, A263715.

Sequence in context: A069081 A126005 A017089 * A304054 A028413 A282226

Adjacent sequences:  A097266 A097267 A097268 * A097270 A097271 A097272

KEYWORD

nonn

AUTHOR

Ray Chandler, Aug 19 2004

STATUS

approved

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Last modified June 21 06:55 EDT 2021. Contains 345358 sequences. (Running on oeis4.)