A244875 Number of magic labelings with magic sum n of 7th graph shown in link.
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
Links
- Colin Barker, Table of n, a(n) for n = 0..1000
- N. J. A. Sloane, Graphs for A244869-A244876.
- R. P. Stanley, Examples of Magic Labelings, Unpublished Notes, 1973 [Cached copy, with permission]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).
Programs
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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
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