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Search: id:A082529
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| A082529 |
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Numbers n such that n divides C(n(n+1),n+1)/n^2. |
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+0
1
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| 1, 60, 210, 572, 910, 935, 936, 1155, 1197, 1309, 1820, 1848, 2030, 2090, 2142, 2145, 2730, 2871, 2964, 3315, 3400, 3857, 3927, 3978, 4028, 4080, 4185, 4199, 4329, 4550, 4669, 4675, 4845, 4884, 5320, 5423, 5681, 5742, 5950, 5985, 6006, 6032, 6235, 6426
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Equivalently, numbers n such that n divides C(n(n+1),n). - David Wasserman (wasserma(AT)spawar.navy.mil), Sep 13 2004
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EXAMPLE
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n = 2: C(6, 3)/4 = 5, which is not divisible by 2, so 2 is not in the sequence.
n = 60: C(60*61, 61)/3600 has 130 digits and is divisible by 60.
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PROGRAM
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(PARI) count = 0; n = 0; while (count < 50, n = n + 1; works = 1; f = factor(n); for (k = 1, matsize(f)[1], p = f[k, 1]; pow = 0; for (i = 1, n, num = n*n + i; while (num%p == 0, pow = pow + 1; num = num/p); num = i; while (num%p == 0, pow = pow - 1; num = num/p)); if (pow < f[k, 2], works = 0)); if (works, print(n); count = count + 1))
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CROSSREFS
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Sequence in context: A001034 A119630 A112827 this_sequence A126248 A068628 A075287
Adjacent sequences: A082526 A082527 A082528 this_sequence A082530 A082531 A082532
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 30 2003
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EXTENSIONS
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More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Sep 13 2004
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