A218812 Hilltop maps: number of 3Xn binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or antidiagonal neighbor in a random 0..3 3Xn array

1, 57, 481, 3969, 31741, 253877, 2030789, 16245185, 129954437, 1039580065, 8316201565, 66526095969, 532180632797, 4257219986565, 34055959366549, 272433271491721, 2179350950489929, 17433885881159533, 139463713657055833

Offset

1,2

Comments

Row 3 of A218810

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 7*a(n-1) +7*a(n-2) +7*a(n-3) +5*a(n-4) +17*a(n-5) +25*a(n-6) +115*a(n-7) +43*a(n-8) +47*a(n-9) +51*a(n-10) +119*a(n-11) +146*a(n-12) +284*a(n-13) -148*a(n-14) -18*a(n-15) -3*a(n-16) -27*a(n-17) +73*a(n-18) -255*a(n-19) -441*a(n-20) -343*a(n-21) -233*a(n-22) -153*a(n-23) -75*a(n-24) -11*a(n-25) +359*a(n-26) +227*a(n-27) +183*a(n-28) +123*a(n-29) +21*a(n-30) +37*a(n-31) -69*a(n-32) -57*a(n-33) -41*a(n-34) -59*a(n-35) -51*a(n-36) -23*a(n-37) +9*a(n-38) +21*a(n-39) +24*a(n-40) +34*a(n-41) +30*a(n-42) +16*a(n-43) +7*a(n-44) -a(n-45) -9*a(n-46) -9*a(n-47) -7*a(n-48) -a(n-49) +a(n-50) +a(n-51) -a(n-52) -a(n-53) -a(n-54) -a(n-55) for n>56

Example

Some solutions for n=3
..0..0..1....0..0..0....1..0..1....1..1..0....0..0..1....1..0..1....0..1..1
..1..1..0....1..1..1....1..1..1....0..0..0....0..1..0....0..1..0....1..1..0
..0..0..0....0..0..0....0..1..0....1..0..1....0..1..1....0..1..1....0..1..0

Crossrefs

Sequence in context: A268260 A184224 A337629 * A290779 A027143 A164786

Adjacent sequences: A218809 A218810 A218811 * A218813 A218814 A218815

Keyword

nonn

Author

R. H. Hardin Nov 06 2012

Status

approved