A183668 Number of (n+1) X 6 0..6 arrays with every 2 X 2 subblock summing to 12.

251991, 678265, 2163831, 7794409, 30722151, 129866905, 580718871, 2719942729, 13245504711, 66684138745, 345524027511, 1836016135849, 9975788408871, 55289617853785, 311957282081751, 1788849555093769, 10410425929802631, 61413654542916025, 366884643431073591, 2217661712999536489

Offset

1,1

Links

Paolo Xausa, Table of n, a(n) for n = 1..1000

Christian Krause, Proof of formula, Jun 13 2026.

Index entries for linear recurrences with constant coefficients, signature (28,-322,1960,-6769,13132,-13068,5040).

Formula

a(n) = 7*7^n + 372*6^n + 3010*5^n + 10808*4^n + 24486*3^n + 39004*2^n + 39962. - Christian Krause, Jun 13 2026

Example

Some solutions for 3 X 6:
..0..6..4..4..0..0....0..6..0..3..3..5....4..0..4..0..3..2....4..4..0..3..1..6
..6..0..2..2..6..6....5..1..5..4..2..2....4..4..4..4..5..2....0..4..4..5..3..2
..0..6..4..4..0..0....0..6..0..3..3..5....2..2..2..2..1..4....4..4..0..3..1..6

Mathematica

A183668[n_] := 7*7^n + 372*6^n + 3010*5^n + 10808*4^n + 24486*3^n + 39004*2^n + 39962;
Array[A183668, 25] (* Paolo Xausa, Jun 16 2026 *)

Crossrefs

Column 5 of A183672.

Sequence in context: A271144 A058004 A272438 * A235025 A237106 A113567

Adjacent sequences: A183665 A183666 A183667 * A183669 A183670 A183671

Keyword

nonn,easy,changed

Author

R. H. Hardin, Jan 06 2011

Extensions

a(12)-a(20) from Christian Krause, Jun 13 2026

Status

approved