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A117961
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Hexagonal numbers with prime indices.
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4
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6, 15, 45, 91, 231, 325, 561, 703, 1035, 1653, 1891, 2701, 3321, 3655, 4371, 5565, 6903, 7381, 8911, 10011, 10585, 12403, 13695, 15753, 18721, 20301, 21115, 22791, 23653, 25425, 32131, 34191, 37401, 38503, 44253, 45451, 49141, 52975, 55611
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OFFSET
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1,1
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COMMENTS
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See also: A034953 Triangular numbers (A000217) with prime indices. A001248 Squares of primes. A116995 Pentagonal numbers with prime indices. A000384 Hexagonal numbers: n(2n-1). There are no prime hexagonal numbers. The n-th Hexagonal number A000384(n) = n*(2*n-1) is semiprime iff both n and 2*n-1 are prime iff A000384(n) is an element of A001358 iff n is an element of A005382.
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LINKS
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FORMULA
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MATHEMATICA
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With[{hex=Table[n(2n-1), {n, 250}]}, Flatten[Table[Take[hex, {Prime[n]}], {n, 40}]]] (* Harvey P. Dale, Dec 04 2011 *)
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CROSSREFS
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KEYWORD
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easy,nonn,less
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AUTHOR
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STATUS
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approved
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