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 A097268 Numbers that are both the sum of two nonzero squares and the difference of two nonzero squares. 24
 5, 8, 13, 17, 20, 25, 29, 32, 37, 40, 41, 45, 52, 53, 61, 65, 68, 72, 73, 80, 85, 89, 97, 100, 101, 104, 109, 113, 116, 117, 125, 128, 136, 137, 145, 148, 149, 153, 157, 160, 164, 169, 173, 180, 181, 185, 193, 197, 200, 205, 208, 212, 221, 225, 229, 232, 233 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Intersection of A000404 (sum of squares) and A024352 (difference of squares). Also: Numbers of the form x^2+4y^2, where x and y are positive integers. Cf. A154777, A092572, A154778 for analogous sequences. - M. F. Hasler, Jan 24 2009 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 Eric Weisstein's World of Mathematics, Sum of Squares Function. PROG (PARI) isA097268(n) = forstep( b=2, sqrtint(n-1), 2, issquare(n-b^2) && return(1)) \\ M. F. Hasler, Jan 24 2009 CROSSREFS Cf. A000404, A024352, A097269, A097270, A097271. Sequence in context: A314424 A314425 A058240 * A226696 A285973 A219639 Adjacent sequences: A097265 A097266 A097267 * A097269 A097270 A097271 KEYWORD nonn AUTHOR Ray Chandler, Aug 19 2004 STATUS approved

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Last modified June 5 21:20 EDT 2023. Contains 363138 sequences. (Running on oeis4.)