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 A081492 Sum of terms in n-th row of A081491. 4
 1, 5, 18, 54, 135, 291, 560, 988, 1629, 2545, 3806, 5490, 7683, 10479, 13980, 18296, 23545, 29853, 37354, 46190, 56511, 68475, 82248, 98004, 115925, 136201, 159030, 184618, 213179, 244935, 280116, 318960, 361713, 408629, 459970, 516006, 577015 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For odd n a(n) is a multiple of n and a(n)/n is the middle term of the corresponding row. LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1). FORMULA a(n) = n*(2*n^3 - 6*n^2 + 13*n - 3)/6. G.f.: x*(1+x)*(1-x+4*x^2)/(1-x)^5. - Colin Barker, Jul 28 2012 E.g.f.: x*(6 +9*x +6*x^2 +2*x^3)/6. - G. C. Greubel, Aug 13 2019 MAPLE seq(n*(2*(n-1)^3+7*n-1)/6, n=1..40); # G. C. Greubel, Aug 13 2019 MATHEMATICA LinearRecurrence[{5, -10, 10, -5, 1}, {1, 5, 18, 54, 135}, 40] (* Harvey P. Dale, Jul 01 2018 *) PROG (PARI) vector(40, n, n*(2*(n-1)^3+7*n-1)/6) \\ G. C. Greubel, Aug 13 2019 (Magma) [n*(2*(n-1)^3+7*n-1)/6: n in [1..40]]; // G. C. Greubel, Aug 13 2019 (Sage) [n*(2*(n-1)^3+7*n-1)/6 for n in (1..40)] # G. C. Greubel, Aug 13 2019 (GAP) List([1..40], n-> n*(2*(n-1)^3+7*n-1)/6); # G. C. Greubel, Aug 13 2019 CROSSREFS Cf. A002522, A005408, A081489, A081490, A081491. Sequence in context: A271771 A270990 A272558 * A263318 A011845 A099450 Adjacent sequences: A081489 A081490 A081491 * A081493 A081494 A081495 KEYWORD nonn,easy AUTHOR Amarnath Murthy, Mar 25 2003 EXTENSIONS More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 29 2003. Formula corrected by Colin Barker, Jul 28 2012 STATUS approved

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Last modified September 18 13:45 EDT 2024. Contains 376000 sequences. (Running on oeis4.)