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 A271998 Volatile sequence: a(n) = A018227(n)-6. 2
 30, 48, 80, 112, 162, 212, 284, 356, 454, 552, 680, 808, 970, 1132, 1332, 1532, 1774, 2016, 2304, 2592, 2930, 3268, 3660, 4052, 4502, 4952, 5464, 5976, 6554, 7132, 7780, 8428, 9150, 9872, 10672, 11472, 12354, 13236, 14204, 15172, 16230, 17288, 18440 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,1 COMMENTS Terms up to 112 are the atomic numbers of the elements of group 12 in the periodic table. The group is also known as the volatile metals since almost all elements with that property fall in to group 12. LINKS Colin Barker, Table of n, a(n) for n = 3..1000 Wikipedia, Group 12 element. Index entries for linear recurrences with constant coefficients, signature (2,1,-4,1,2,-1). FORMULA From Colin Barker, Oct 25 2016: (Start) G.f.: 2*x^3*(15 - 6*x - 23*x^2 + 12*x^3 + 10*x^4 - 6*x^5)/((1 - x)^4*(1 + x)^2). a(n) = 2*a(n-1) + a(n-2) - 4*a(n-3) + a(n-4) + 2*a(n-5) - a(n-6) for n>8. a(n) = (n^3 + 9*n^2 + 26*n - 24)/6 for n even. a(n) = (n^3 + 9*n^2 + 29*n - 15)/6 for n odd. (End) MATHEMATICA LinearRecurrence[{2, 1, -4, 1, 2, -1}, {30, 48, 80, 112, 162, 212}, 50] (* Harvey P. Dale, Mar 07 2022 *) PROG (PARI) Vec(2*x^3*(15-6*x-23*x^2+12*x^3+10*x^4-6*x^5)/((1-x)^4*(1+x)^2) + O(x^60)) \\ Colin Barker, Oct 25 2016 CROSSREFS Sequence in context: A004223 A230558 A272949 * A365965 A307130 A228097 Adjacent sequences: A271995 A271996 A271997 * A271999 A272000 A272001 KEYWORD nonn,easy AUTHOR Natan Arie Consigli, Jun 27 2016 STATUS approved

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Last modified July 22 19:00 EDT 2024. Contains 374540 sequences. (Running on oeis4.)