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Search: id:A051875
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| A051875 |
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23-gonal numbers: n(21n-19)/2. |
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+0
1
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| 0, 1, 23, 66, 130, 215, 321, 448, 596, 765, 955, 1166, 1398, 1651, 1925, 2220, 2536, 2873, 3231, 3610, 4010, 4431, 4873, 5336, 5820, 6325, 6851, 7398, 7966, 8555, 9165, 9796, 10448, 11121, 11815, 12530, 13266, 14023, 14801, 15600
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, p. 189.
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FORMULA
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a(n)=21*n+a(n-1)-41 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 13 2009]
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EXAMPLE
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For n=2, a(2)=21*2+0-41=1; n=3, a(3)=21*3+1-41=23; n=4, a(4)=21*4+23-41=66 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 13 2009]
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MATHEMATICA
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s=0; lst={s}; Do[s+=n++ +1; AppendTo[lst, s], {n, 0, 7!, 21}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 16 2008]
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CROSSREFS
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Sequence in context: A107692 A089823 A001346 this_sequence A125872 A104945 A141849
Adjacent sequences: A051872 A051873 A051874 this_sequence A051876 A051877 A051878
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Dec 15 1999
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