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A129654
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Number of different ways to represent n as general polygonal number P(m,r) = 1/2*r*((m-2)*r-(m-4)) = n>1, for m,r>1.
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2
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1, 2, 2, 2, 3, 2, 2, 3, 3, 2, 3, 2, 2, 4, 3, 2, 3, 2, 2, 4, 3, 2, 3, 3, 2, 3, 4, 2, 3, 2, 2, 3, 3, 3, 5, 2, 2, 3, 3, 2, 3, 2, 2, 5, 3, 2, 3, 3, 2, 4, 3, 2, 3, 4, 2, 3, 3, 2, 3, 2, 2, 3, 4, 3, 5, 2, 2, 3, 4, 2, 3, 2, 2, 4, 3, 2, 4, 2, 2, 5, 3, 2, 3, 3, 2, 3, 3, 2, 3, 4, 3, 3, 3, 3, 4, 2, 2, 3, 4, 2, 3, 2, 2, 5, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,2
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COMMENTS
| The indices k of the first appearance of number n in a(k) are listed in A063778(n) = {2,3,6,15,36,225,...} = Least number k>1 such that k could be represented in n different ways as general m-gonal number P(m,r) = 1/2*r*((m-2)*r-(m-4)).
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LINKS
| Eric Weisstein, Link to a section of The World of Mathematics, Polygonal Number.
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FORMULA
| a(n) = A177025(n) + 1.
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EXAMPLE
| a(6) = 3 because 6 = P(2,6) = P(3,3) = P(6,2).
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CROSSREFS
| Cf. A063778.
Sequence in context: A085694 A160493 A053760 * A138789 A116504 A186233
Adjacent sequences: A129651 A129652 A129653 * A129655 A129656 A129657
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KEYWORD
| nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Apr 27 2007
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