The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A295171 Chromatic invariant of the n-crown graph. 1
 1, 11, 328, 16369, 1181276, 116093641, 14916610346, 2428960220241, 489039354264712, 119323954705155265, 34701518665828422926, 11861024763916090258105, 4708209994260510940754540, 2148158302978435764574475817, 1116465105383647067485461486754 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,2 LINKS Andrew Howroyd, Table of n, a(n) for n = 3..100 Eric Weisstein's World of Mathematics, Chromatic Invariant Eric Weisstein's World of Mathematics, Crown Graph FORMULA a(n) = Sum_{k=2..2*n} Sum_{j=0..n} Sum_{i=0..k-j} (-1)^k*(k-2)!*binomial(n, j)*Stirling2(n-j, i)*Stirling2(n-j, k-j-i). - Andrew Howroyd, Apr 22 2018 MATHEMATICA Table[Sum[(-1)^k (k - 2)! Binomial[n, j] StirlingS2[n - j, i] StirlingS2[n - j, k - j - i], {k, 2, 2 n}, {j, 0, n}, {i, 0, k - j}], {n, 3, 20}] (* Eric W. Weisstein, Apr 23 2018 *) PROG (PARI) a(n)={sum(k=2, 2*n, (-1)^k*(k-2)!*sum(j=0, min(n, k), binomial(n, j)*sum(i=0, k-j, stirling(n-j, i, 2)*stirling(n-j, k-j-i, 2))))} \\ Andrew Howroyd, Apr 22 2018 CROSSREFS Sequence in context: A241127 A268551 A108274 * A254545 A160293 A084944 Adjacent sequences: A295168 A295169 A295170 * A295172 A295173 A295174 KEYWORD nonn AUTHOR Eric W. Weisstein, Nov 16 2017 EXTENSIONS Terms a(10) and beyond from Andrew Howroyd, Apr 22 2018 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 24 22:14 EDT 2023. Contains 365582 sequences. (Running on oeis4.)