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A064226
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(9*n^2+13*n+6)/2.
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6
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3, 14, 34, 63, 101, 148, 204, 269, 343, 426, 518, 619, 729, 848, 976, 1113, 1259, 1414, 1578, 1751, 1933, 2124, 2324, 2533, 2751, 2978, 3214, 3459, 3713, 3976, 4248, 4529, 4819, 5118, 5426, 5743, 6069, 6404, 6748, 7101, 7463, 7834, 8214, 8603, 9001, 9408
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| Diagonal of triangular spiral in A051682. - Paul Barry (pbarry(AT)wit.ie), Mar 15 2003
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REFERENCES
| National Security Agency, advertisement in Notices of the Amer. Math. Soc., vol. 49 (2001), p. 216.
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LINKS
| Harry J. Smith, Table of n, a(n) for n=0,...,1000
Milan Janjic, Two Enumerative Functions
Index entries for sequences related to linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| a(n)=3C(n, 0)+11C(n, 1)+9C(n, 2); binomial transform of (3, 11, 9, 0, 0, 0, .....). a(n)=(9n^2+13n+6)/2. G.f.(3+5x+x^2)/(1-x)^3. - Paul Barry (pbarry(AT)wit.ie), Mar 15 2003
Ehrhart polynomial of open quadrilateral with vertices (0,2),(2,3),(3,1),(2,0). - Michael Somos Jul 22 2006
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PROG
| (PARI) a(n)=3+n*(9*n+13)/2 /* Michael Somos Jul 22 2006 */
(PARI) { for (n=0, 1000, write("b064226.txt", n, " ", 3 + n*(9*n + 13)/2) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 10 2009]
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CROSSREFS
| a(n)=A081268(n)+2. Cf. A051682, A081267.
A064225(n)=a(-1-n).
Sequence in context: A155154 A081269 A140064 * A077288 A094627 A009394
Adjacent sequences: A064223 A064224 A064225 * A064227 A064228 A064229
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Sep 22 2001
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