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 A006597 a(n) = n^2*(5*n-3)/2. 5
 0, 1, 14, 54, 136, 275, 486, 784, 1184, 1701, 2350, 3146, 4104, 5239, 6566, 8100, 9856, 11849, 14094, 16606, 19400, 22491, 25894, 29624, 33696, 38125, 42926, 48114, 53704, 59711, 66150, 73036, 80384, 88209, 96526, 105350, 114696, 124579, 135014, 146016 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Structured heptagonal prism numbers. - James A. Record (james.record(AT)gmail.com), Nov 07 2004 Apart from 0, partial sums of A220083. [Bruno Berselli, Dec 11 2012] REFERENCES W. A. Whitworth, DCC Exercises in Choice and Chance, Stechert, NY, 1945, p. 29. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..10000 Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1). FORMULA a(n) = (1/6)*(15*n^3-9*n^2). - James A. Record (james.record(AT)gmail.com), Nov 07 2004 G.f.: x*(1+10*x+4*x^2)/(1-x)^4. - Colin Barker, Jun 08 2012 a(n) = Sum_{i=0..n-1} n*(5*i+1) for n>0. [Bruno Berselli, Sep 08 2015] Sum_{n>=1} 1/a(n) = 1.1080093773051638036... = (sqrt(5*(5 - 2*sqrt(5)))*Pi - Pi^2 - 5*sqrt(5)*arccoth(sqrt(5)) + (25*log(5))/2)/9. - Vaclav Kotesovec, Oct 04 2016 MAPLE A006597:=n->n^2*(5*n-3)/2; seq(A006597(n), n=0..40); # Wesley Ivan Hurt, Mar 11 2014 MATHEMATICA Table[n^2*(5*n-3)/2, {n, 0, 40}] (* Wesley Ivan Hurt, Mar 11 2014 *) PROG (MAGMA) [n^2*(5*n-3)/2: n in [0..40]]; // Vincenzo Librandi, Jul 20 2011 (PARI) a(n)=n^2*(5*n-3)/2; \\ Joerg Arndt, Jul 20 2011 CROSSREFS Cf. A100177 - structured prisms; A100145 for more on structured numbers. Cf. similar sequences, with the formula (k*n-k+2)*n^2/2, listed in A262000. Sequence in context: A118530 A048971 A299646 * A304294 A114012 A140784 Adjacent sequences:  A006594 A006595 A006596 * A006598 A006599 A006600 KEYWORD nonn,easy AUTHOR EXTENSIONS Name corrected by Arkadiusz Wesolowski, Jul 20 2011 STATUS approved

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Last modified January 22 07:46 EST 2019. Contains 319357 sequences. (Running on oeis4.)