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A102646
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Numbers of form j k^2 with 1 <= j <= k, gcd(j,k) = 1.
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3
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1, 4, 9, 16, 18, 25, 36, 48, 49, 50, 64, 75, 81, 98, 100, 121, 144, 147, 162, 169, 180, 192, 196, 225, 242, 245, 256, 289, 294, 300, 320, 324, 338, 361, 363, 400, 405, 441, 448, 450, 484, 507, 529, 567, 576, 578, 588, 605, 625, 648, 676, 700, 720, 722, 726, 729
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OFFSET
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1,2
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COMMENTS
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Numbers n such that A102448(n) >= 1.
All positive squares x^2 are in the sequence with j = 1, k = x.
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LINKS
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EXAMPLE
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180 is in the sequence with j = 5, k = 6.
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PROG
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(PARI) is(n) = {my(f = factor(n), podd = 1, peven = 1); for(i = 1, #f~, if(bittest(f[i, 2], 0), podd *= f[i, 1]^f[i, 2] , peven *= f[i, 1]^(f[i, 2] >> 1) ) ); podd <= peven } \\ David A. Corneth, Nov 11 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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