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0, 9, 20, 33, 48, 65, 84, 105, 128, 153, 180, 209, 240, 273, 308, 345, 384, 425, 468, 513, 560, 609, 660, 713, 768, 825, 884, 945, 1008, 1073, 1140, 1209, 1280, 1353, 1428, 1505, 1584, 1665, 1748, 1833, 1920, 2009, 2100, 2193, 2288, 2385
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| P. De Geest, Palindromic Quasipronics of the form n(n+x)
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FORMULA
| a(n)= (n+4)^2 -4^2 = n*(n+8), n>=0.
G.f.: x*(9-7*x)/(1-x)^3.
a(n)=2*n+a(n-1)+7. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 05 2010]
sum_{n>=1} 1/a(n) = 761/2240 = 0.3397321.. - R. J. Mathar, Mar 22 2011
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MAPLE
| with(finance):seq(add(cashflows([k, k, 7], 0 ), k=1..n), n=0..45); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 22 2008]
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MATHEMATICA
| s=0; lst={s}; Do[s+=n++ +9; AppendTo[lst, s], {n, 0, 6!, 2}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 16 2008]
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PROG
| (Other) SAGE: [lucas_number2(2, n, 7-n)-1 for n in xrange(3, 49)]# [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 12 2009]
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CROSSREFS
| a(n-4), n>=5, fourth column (used for the Brackett series of the hydrogen atom) of triangle A120070.
Sequence in context: A094196 A017497 A059108 * A147479 A146680 A143704
Adjacent sequences: A028563 A028564 A028565 * A028567 A028568 A028569
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KEYWORD
| nonn
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com)
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