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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 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 (Python) from itertools import count, islice from sympy import factorint def A097269_gen(): # generator of terms     return filter(lambda n:all(p & 3 != 3 or e & 1 == 0 for p, e in factorint(n//2).items()), count(2, 4)) A097269_list = list(islice(A097269_gen(), 30)) # Chai Wah Wu, Jun 28 2022 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,changed AUTHOR Ray Chandler, Aug 19 2004 STATUS approved

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Last modified July 7 00:24 EDT 2022. Contains 355115 sequences. (Running on oeis4.)