A225978 Number of nX4 binary arrays whose sum with another nX4 binary array containing no more than two 1s has rows and columns in lexicographically nondecreasing order.
15, 138, 1178, 9113, 61808, 361361, 1825607, 8065278, 31631401, 111785599, 360788468, 1075829429, 2993017696, 7832960008, 19417916324, 45865067963, 103734768130, 225619306783, 473616394498, 962612525277, 1899542726132
Offset: 1
Keywords
Examples
Some solutions for n=3 ..0..0..0..1....0..0..1..1....0..0..1..1....0..0..0..1....0..0..0..1 ..0..1..0..1....0..0..0..0....1..0..0..0....1..1..1..0....0..0..0..1 ..1..0..1..1....1..0..0..1....0..0..0..1....0..1..0..0....1..1..0..1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..76
Formula
Empirical: a(n) = (23/14820309504000)*n^17 + (397/2615348736000)*n^16 + (1429/217945728000)*n^15 + (21083/130767436800)*n^14 + (156407/62270208000)*n^13 + (375707/14370048000)*n^12 + (3136061/16765056000)*n^11 + (21563/22861440)*n^10 + (26402329/6096384000)*n^9 + (423919927/18289152000)*n^8 + (68634593/598752000)*n^7 + (144700261/1437004800)*n^6 + (19312991563/12108096000)*n^5 - (22496273857/4540536000)*n^4 + (97668459683/3027024000)*n^3 - (41460631/700700)*n^2 + (20134601/291720)*n - 23 for n>2
Comments