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Search: id:A155710
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| A155710 |
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Intersection of A092572 and A154778: N = a^2 + 3b^2 = c^2 + 5d^2 for some positive integers a,b,c,d. |
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+0
2
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| 21, 36, 49, 61, 84, 109, 129, 144, 181, 189, 196, 201, 229, 241, 244, 301, 309, 324, 336, 349, 381, 409, 421, 436, 441, 469, 489, 516, 525, 541, 549, 576, 601, 661, 669, 709, 721, 724, 756, 769, 784, 804, 829, 849, 889, 900, 916, 921, 964, 976, 981, 1009, 1021
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Subsequence of A155570 (where a,b,c,d may be zero).
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PROGRAM
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(PARI) isA155710(n, /* use optional 2nd arg to get other analogous sequences */c=[5, 3]) = { for(i=1, #c, for(b=1, sqrtint((n-1)\c[i]), issquare(n-c[i]*b^2) & next(2)); return); 1}
for( n=1, 1111, isA155710(n) & print1(n", "))
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CROSSREFS
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Cf. A000404, A154777, A092572, A097268, A154778, A155716, ...
Sequence in context: A008946 A095738 A138227 this_sequence A001491 A112352 A067598
Adjacent sequences: A155707 A155708 A155709 this_sequence A155711 A155712 A155713
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KEYWORD
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easy,nonn
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AUTHOR
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M. F. Hasler (MHasler(AT)univ-ag.fr), Jan 25 2009
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