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A015223
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Odd pentagonal pyramidal numbers.
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5
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1, 75, 405, 1183, 2601, 4851, 8125, 12615, 18513, 26011, 35301, 46575, 60025, 75843, 94221, 115351, 139425, 166635, 197173, 231231, 269001, 310675, 356445, 406503, 461041, 520251, 584325, 653455, 727833, 807651, 893101, 984375
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Also first bisection of A139757. - Bruno Berselli, Feb 13 2012
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LINKS
| Bruno Berselli, Table of n, a(n) for n = 0..1000
Eric Weisstein's World of Mathematics, Pentagonal Pyramidal Number
Index entries for sequences related to linear recurrences with constant coefficients, signature (4,-6,4,-1).
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FORMULA
| G.f.: (1+71*x+111*x^2+9*x^3)/(1-x)^4. - Colin Barker, Feb 13 2012
a(n) = (2*n+1)*(4*n+1)^2 = A130656(4*n+1). - Bruno Berselli, Feb 13 2012
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MATHEMATICA
| Table[((n+1)^3+(n+1)^2)/2, {n, 0, 200, 4}] (* From Vladimir Joseph Stephan Orlovsky, May 21 2011 *)
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CROSSREFS
| Cf. A002411, A014799, A015224, A014800.
Sequence in context: A158765 A055561 A193252 * A129625 A133382 A199901
Adjacent sequences: A015220 A015221 A015222 * A015224 A015225 A015226
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KEYWORD
| nonn,easy,changed
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AUTHOR
| Mohammad K. Azarian (ma3(AT)evansville.edu)
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EXTENSIONS
| More terms from Erich Friedman (erich.friedman(AT)stetson.edu).
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