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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
Wikipedia, Group 12 element.
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
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.)