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A374286
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a(n) is the smallest nonnegative integer k where there are exactly n nonnegative integer solutions to x^2 + 3*y^2 = k.
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2
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2, 0, 4, 28, 1729, 196, 364, 1529437, 9604, 2548, 593047, 470596, 6916, 68574961, 33124, 124852, 1983163
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OFFSET
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0,1
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COMMENTS
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a(n) is the smallest nonnegative k such that A119395(k) = n.
a(18) = 48412.
a(20) = 18384457.
a(21) = 6117748.
a(23) = 1623076.
a(24) = 214396.
a(27) = 629356.
a(30) = 2372188.
a(32) = 79530724.
a(36) = 1500772.
a(41) = 11957764.
a(42) = 116237212.
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LINKS
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PROG
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(PARI) b(n, k) = sum(i=0, sqrtint(n), sum(j=0, sqrtint(n\k), i^2+k*j^2==n));
a(n, k=3) = my(cnt=0); while(b(cnt, k)!=n, cnt++); cnt;
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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