login
A244875
Number of magic labelings with magic sum n of 7th graph shown in link.
2
1, 21, 179, 938, 3612, 11242, 29947, 70855, 152720, 305330, 573812, 1023939, 1748545, 2875153, 4574922, 7073018, 10660515, 15707931, 22680505, 32155320, 44840378, 61595732, 83456781, 111659833, 147670042, 193211824, 250301858, 321284777, 408871655, 516181395
OFFSET
0,2
LINKS
R. P. Stanley, Examples of Magic Labelings, Unpublished Notes, 1973 [Cached copy, with permission]
Index entries for linear recurrences with constant coefficients, signature (7,-20,28,-14,-14,28,-20,7,-1).
FORMULA
G.f.: (1 + 14*x + 52*x^2 + 77*x^3 + 52*x^4 + 14*x^5 + x^6) / ((1 - x)^8*(1 + x)).
a(n) = (315*(255+(-1)^n) + 306144*n + 498456*n^2 + 452312*n^3 + 250530*n^4 + 86576*n^5 + 17724*n^6 + 1688*n^7) / 80640. - Colin Barker, Jan 11 2017
PROG
(PARI) Vec((1 + 14*x + 52*x^2 + 77*x^3 + 52*x^4 + 14*x^5 + x^6) / ((1 - x)^8*(1 + x)) + O(x^40)) \\ Colin Barker, Jan 11 2017
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Jul 08 2014
STATUS
approved