A303521 Number of nX4 0..1 arrays with every element equal to 0, 1, 3, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

5, 21, 37, 103, 340, 1115, 4112, 16640, 71025, 320957, 1510853, 7287031, 35723065, 176869202, 880763327, 4401181230, 22037652351, 110478062574, 554227859714, 2781487076749, 13962670138510, 70100301160570, 351970530142109

Offset

1,1

Comments

Column 4 of A303525.

Links

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

Formula

Empirical: a(n) = 7*a(n-1) -9*a(n-2) +8*a(n-3) -68*a(n-4) +8*a(n-5) -6*a(n-6) +260*a(n-7) +444*a(n-8) +617*a(n-9) -488*a(n-10) -858*a(n-11) -2426*a(n-12) -1778*a(n-13) -2233*a(n-14) +1090*a(n-15) +2944*a(n-16) +5714*a(n-17) +4242*a(n-18) +1676*a(n-19) -5030*a(n-20) -6560*a(n-21) -3203*a(n-22) +5344*a(n-23) +11678*a(n-24) +10874*a(n-25) +8003*a(n-26) -6178*a(n-27) -11743*a(n-28) -18221*a(n-29) -11933*a(n-30) -7346*a(n-31) +3388*a(n-32) +8166*a(n-33) +9709*a(n-34) +6270*a(n-35) +2172*a(n-36) -1377*a(n-37) -2343*a(n-38) -1877*a(n-39) -576*a(n-40) +51*a(n-41) +210*a(n-42) +170*a(n-43) +22*a(n-44) -13*a(n-45) -31*a(n-46) -9*a(n-47) for n>49

Example

Some solutions for n=5
..0..1..0..0. .0..1..1..1. .0..0..0..1. .0..1..1..0. .0..1..1..0
..0..0..1..0. .0..1..0..1. .0..1..1..1. .0..1..0..1. .1..0..1..0
..1..1..1..1. .0..1..0..1. .0..1..0..1. .0..1..0..1. .1..0..1..0
..1..0..1..1. .0..1..1..1. .0..0..0..1. .0..1..0..1. .1..0..1..0
..1..0..1..0. .0..1..0..0. .0..1..0..1. .0..1..0..1. .1..0..1..0

Crossrefs

Cf. A303525.

Sequence in context: A170876 A341198 A038844 * A365767 A147345 A146022

Adjacent sequences: A303518 A303519 A303520 * A303522 A303523 A303524

Keyword

nonn

Author

R. H. Hardin, Apr 25 2018

Status

approved