A220795 Equals two maps: number of 2Xn binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal, diagonal and antidiagonal neighbors in a random 0..2 2Xn array

1, 6, 19, 76, 267, 1074, 4069, 15916, 62161, 243418, 954189, 3745072, 14698115, 57707746, 226582983, 889710492, 3493659533, 13718948094, 53871964175, 211547211964, 830715606031, 3262105325370, 12809842147609, 50302517147348

Offset

1,2

Comments

Row 2 of A220794

Links

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

Formula

Empirical: a(n) = 4*a(n-1) +10*a(n-2) -34*a(n-3) -66*a(n-4) +98*a(n-5) +320*a(n-6) -66*a(n-7) -916*a(n-8) -306*a(n-9) +1454*a(n-10) +1054*a(n-11) -1038*a(n-12) -1690*a(n-13) -376*a(n-14) +1514*a(n-15) +1301*a(n-16) -1114*a(n-17) -1008*a(n-18) +796*a(n-19) -568*a(n-20) -624*a(n-21) +720*a(n-22) -144*a(n-23) +64*a(n-24) +64*a(n-25)

Example

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

Crossrefs

Sequence in context: A100191 A191585 A359190 * A026545 A041937 A279512

Adjacent sequences: A220792 A220793 A220794 * A220796 A220797 A220798

Keyword

nonn

Author

R. H. Hardin Dec 21 2012

Status

approved