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A160970
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Indices of square numbers which are also 18-gonal numbers.
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0
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0, 1, 10, 44, 341, 1495, 11584, 50786, 393515, 1725229, 13367926, 58607000, 454115969, 1990912771, 15426575020, 67632427214, 524049434711, 2297511612505, 17802254205154, 78047762397956, 604752593540525, 2651326409917999, 20543785926172696, 90067050174814010
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Solving the Diophantine equation A051870(m) = m*(8*m-7) = k^2 leads to the entries.
k in the sequence and a list of associated m= 0, 1, 4, 16, 121, 529, 4096, 17956, 139129, 609961...
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FORMULA
| Conjecture: a(n) = 34*a(n-2)-a(n-4), n>5. [R. J. Mathar, Oct 04 2009]
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MATHEMATICA
| LinearRecurrence[{0, 34, 0, -1, 0}, {0, 1, 10, 44, 341}, 50] (* T. D. Noe, Nov 07 2011 *)
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CROSSREFS
| Sequence in context: A126397 A164607 A200189 * A202296 A199350 A199516
Adjacent sequences: A160967 A160968 A160969 * A160971 A160972 A160973
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KEYWORD
| nonn
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AUTHOR
| Sture Sjoestedt (sture.sjostedt(AT)spray.se), Jun 01 2009, Jul 02 2009
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EXTENSIONS
| 0 added in front and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 04 2009
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