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 A116471 Values 2*(n -+ 1)^2 sorted. 5
 0, 2, 8, 8, 18, 18, 32, 32, 50, 50, 72, 72, 98, 98, 128, 128, 162, 162, 200, 200, 242, 242, 288, 288, 338, 338, 392, 392, 450, 450, 512, 512, 578, 578, 648, 648, 722, 722, 800, 800, 882, 882, 968, 968, 1058, 1058, 1152, 1152, 1250, 1250, 1352, 1352, 1458, 1458 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For n>2, consists of entries of A001105(n)=2*n^2 (n>1) that appear twice. The terms a(2)-a(8) give the number of elements in the periods 1-7 of the periodic table of the chemical elements. - Antti Karttunen, Aug 14 2008 LINKS Muniru A Asiru, Table of n, a(n) for n = 1..5000 Wikipedia, Atomic electron configuration table Wikipedia, Periodic table Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1). FORMULA a(2n) = A001105(n) for n >= 1. a(n) = a(n-1) + 2*a(n-2) - 2*a(n-3)- a(n-4) + a(n-5). - Colin Barker, Oct 06 2014 G.f.: -2*x^2*(x^4 - x^3 - 2*x^2 + 3*x + 1) / ((x-1)^3*(x+1)^2). - Colin Barker, Oct 06 2014 a(n) = ( 2*n^2 + 2*n - (2*n+1)*(-1)^n + 1 )/4, with n > 1 and a(1)=0. - Bruno Berselli, Oct 07 2014 a(n) = A001057(n+1) + A000217(n+1) for n > 1. - Andrew S. Plewe, Sep 24 2018 MAPLE 0, seq(op([2*n^2, 2*n^2]), n=1..30); # Muniru A Asiru, Oct 25 2018 MATHEMATICA Rest@ Flatten@ Table[2 (n #)^2 & /@ {-1, 1}, {n, 0, 27}] (* or *) Rest@ CoefficientList[Series[-2 x^2 (x^4 - x^3 - 2 x^2 + 3 x + 1)/((x - 1)^3 (x + 1)^2), {x, 0, 54}], x] (* Michael De Vlieger, Jul 22 2016 *) PROG (PARI) concat(0, Vec(-2*x^2*(x^4-x^3-2*x^2+3*x+1)/((x-1)^3*(x+1)^2) + O(x^100))) \\ Colin Barker, Oct 06 2014 (GAP) a:=[2, 8, 8, 18, 18];;  for n in [6..54] do a[n]:=a[n-1]+2*a[n-2]-2*a[n-3]-a[n-4]+a[n-5]; od; Concatenation([0], a); # Muniru A Asiru, Oct 25 2018 CROSSREFS Cf. A001105, A093907, A016742. Sequence in context: A019240 A269510 A093907 * A146749 A250313 A180825 Adjacent sequences:  A116468 A116469 A116470 * A116472 A116473 A116474 KEYWORD nonn,easy AUTHOR Lekraj Beedassy, Mar 17 2006 EXTENSIONS More terms from Joshua Zucker, May 11 2006 STATUS approved

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Last modified December 13 06:26 EST 2019. Contains 329968 sequences. (Running on oeis4.)