OFFSET
2,1
COMMENTS
a(n+1) / a(n) tends to 8.597218255461742020947886618374491114891840151635008721734194641555448999... - Vaclav Kotesovec, Nov 24 2020
LINKS
Seiichi Manyama, Table of n, a(n) for n = 2..500
Eric Weisstein's World of Mathematics, Graph Cycle
Eric Weisstein's World of Mathematics, Grid Graph
FORMULA
Empirical g.f.: -x^2*(10 - 42*x + 149*x^2 - 300*x^3 - 393*x^4 + 693*x^5 + 230*x^6 - 473*x^7 - 72*x^8 + 202*x^9 + 84*x^10) / ((1 - x)^2 * (-1 + 13*x - 45*x^2 + 66*x^3 - 17*x^4 - 209*x^5 + 151*x^6 + 140*x^7 - 112*x^8 - 48*x^9 + 50*x^10 + 28*x^11)). - Vaclav Kotesovec, Nov 24 2020
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 24 2020
STATUS
approved