

A263231


a(n) = n*(25*n  39)/2.


5



0, 7, 11, 54, 122, 215, 333, 476, 644, 837, 1055, 1298, 1566, 1859, 2177, 2520, 2888, 3281, 3699, 4142, 4610, 5103, 5621, 6164, 6732, 7325, 7943, 8586, 9254, 9947, 10665, 11408, 12176, 12969, 13787, 14630, 15498, 16391, 17309, 18252, 19220
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OFFSET

0,2


COMMENTS

For n>=3, a(n) = the hyperWiener index of the Jahangir graph J_{2,n}. The Jahangir graph J_{2,n} is a connected graph consisting of a cycle graph C(2n) and one additional center vertex that is adjacent to n vertices of C(2n) at distances 2 to each other on C(2n).
The Hosoya polynomial of J_{2,n} is 3nx + n(n+3))x^2/2 + n(n2)x^3 +n(n3)x^4/2.


REFERENCES

M. R. Farahani, Hosoya polynomial and Wiener index of Jahangir graphs J_{2,m}, Pacific J. Appl. Math, 7 (3), 2015.


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000
Index entries for linear recurrences with constant coefficients, signature (3,3,1).


FORMULA

G.f.: x*(32*x7)/(1x)^3.
a(n) = 3*a(n1)  3*a(n2) + a(n3).


MAPLE

seq((25*n^2  39*n)/2, n=0..40);


MATHEMATICA

Table[n (25 n  39)/2, {n, 0, 40}]


PROG

(PARI) vector(50, n, n; n*(25*n39)/2)
(PARI) concat(0, Vec(x*(32*x7)/(1x)^3 + O(x^100))) \\ Altug Alkan, Oct 18 2015
(Haskell)
a263231 n = n * (25 * n  39) `div` 2
a263231_list = 0 : 7 : 11 : zipWith (+) a263231_list
(map (* 3) $ tail $ zipWith () (tail a263231_list) a263231_list)
 Reinhard Zumkeller, Nov 04 2015


CROSSREFS

Cf. A263226, A263227, A263228, A263229, A263230.
Sequence in context: A018508 A038277 A045462 * A077411 A085016 A067690
Adjacent sequences: A263228 A263229 A263230 * A263232 A263233 A263234


KEYWORD

sign,easy


AUTHOR

Emeric Deutsch, Oct 14 2015


STATUS

approved



