A220636 Number of ways to reciprocally link elements of an 6Xn array either to themselves or to exactly two horizontal or antidiagonal neighbors.
1, 1, 13, 351, 8560, 183961, 3817452, 79063898, 1643423543, 34184820039, 711142299027, 14793696906106, 307746212613995, 6401868705356519, 133174202661890384, 2770341001987547086, 57629691849567578540
Offset: 1
Keywords
Examples
Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10) .00.67.47...00.67.47...00.67.47...00.00.00...00.00.00...00.00.00...00.67.47 .36.34.00...36.34.00...36.34.00...00.67.47...00.00.00...00.00.00...36.34.00 .00.00.00...00.67.47...00.00.00...36.34.00...00.67.47...00.67.47...00.00.00 .00.00.00...36.34.00...00.00.00...00.00.00...36.34.00...36.34.00...00.67.47 .00.67.47...00.00.00...00.00.00...00.00.00...00.67.47...00.00.00...36.34.00 .36.34.00...00.00.00...00.00.00...00.00.00...36.34.00...00.00.00...00.00.00
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = 32*a(n-1) -195*a(n-2) -1350*a(n-3) +10665*a(n-4) +31692*a(n-5) -206199*a(n-6) -507142*a(n-7) +1799954*a(n-8) +4606048*a(n-9) -7358332*a(n-10) -21711948*a(n-11) +13920815*a(n-12) +54513592*a(n-13) -9084809*a(n-14) -73913886*a(n-15) -4653883*a(n-16) +53601160*a(n-17) +7698097*a(n-18) -21029870*a(n-19) -3072503*a(n-20) +4411176*a(n-21) +533603*a(n-22) -476894*a(n-23) -41967*a(n-24) +24240*a(n-25) +1155*a(n-26) -450*a(n-27) for n>32
Comments