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Search: id:A064225
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| 1, 8, 24, 49, 83, 126, 178, 239, 309, 388, 476, 573, 679, 794, 918, 1051, 1193, 1344, 1504, 1673, 1851, 2038, 2234, 2439, 2653, 2876, 3108, 3349, 3599, 3858, 4126, 4403, 4689, 4984, 5288, 5601, 5923, 6254, 6594, 6943, 7301, 7668, 8044, 8429, 8823, 9226
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Diagonal of triangular spiral in A051682. - Michael Somos Jul 22 2006
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REFERENCES
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National Security Agency, Notices of the AMS, vol. 49 (2001), p. 216.
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LINKS
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Harry J. Smith, Table of n, a(n) for n=0,...,1000
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FORMULA
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Ehrhart polynomial of closed quadrilateral with vertices (0,2),(2,3),(3,1),(2,0). - Michael Somos Jul 22 2006
a(n)=9*n+a(n-1)-11 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 10 2009]
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EXAMPLE
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For n=2, a(2)=9*2+1-11=8; n=3, a(3)=9*3+8-11=24; n=4, a(4)=9*4+24-11=49 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 10 2009]
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PROGRAM
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(PARI) a(n)=1+n*(9*n+5)/2 /* Michael Somos Jul 22 2006 */
(PARI) { for (n=0, 1000, write("b064225.txt", n, " ", 1 + n*(9*n + 5)/2) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 10 2009]
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CROSSREFS
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A064226(n)=a(-1-n).
Sequence in context: A146980 A028612 A068857 this_sequence A054275 A122655 A152134
Adjacent sequences: A064222 A064223 A064224 this_sequence A064226 A064227 A064228
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KEYWORD
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nonn,new
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Sep 22 2001
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