login
A223462
6X6X6 triangular graph without horizontal edges coloring a rectangular array: number of nX3 0..20 arrays where 0..20 label nodes of a graph with edges 0,1 0,2 1,3 1,4 2,4 2,5 3,6 3,7 4,7 4,8 5,8 5,9 6,10 6,11 7,11 7,12 8,12 8,13 9,13 9,14 10,15 10,16 11,16 11,17 12,17 12,18 13,18 13,19 14,19 14,20 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph
1
190, 2840, 47100, 789796, 13504044, 231085748, 3988872656, 68744309868, 1190949680204, 20584337901440, 357143742858616, 6180644127657520, 107304034484773564, 1858033330929059492, 32266796953842297480
OFFSET
1,1
COMMENTS
Column 3 of A223467
LINKS
FORMULA
Empirical: a(n) = 751*a(n-2) -213977*a(n-4) +30621250*a(n-6) -2460992507*a(n-8) +119254462102*a(n-10) -3670996485078*a(n-12) +75009157476789*a(n-14) -1056588922332331*a(n-16) +10576074147463216*a(n-18) -76959427833100718*a(n-20) +413739436651265546*a(n-22) -1660689308745581771*a(n-24) +5005542176662370394*a(n-26) -11348860916160032402*a(n-28) +19319641870299497561*a(n-30) -24574099114255799068*a(n-32) +23182072953460411397*a(n-34) -16063563012586221221*a(n-36) +8081476839997677366*a(n-38) -2910695207618822958*a(n-40) +737493263291407444*a(n-42) -128540692908762460*a(n-44) +14965848663295632*a(n-46) -1117954806914792*a(n-48) +50415617089984*a(n-50) -1228263380544*a(n-52) +12208371840*a(n-54) for n>55
EXAMPLE
Some solutions for n=3
.17.12..7....6.11.17....4..1..0....2..5..8....4..2..5....5..8.13...11..6.10
.11..7..3...11..7.11....2..4..1....0..2..4....8..4..8....8.12..8....6.10..6
..7..3..1...17.11..7....4..1..3....1..0..1....5..2..4....5..8..5...10.16.10
CROSSREFS
Sequence in context: A258725 A232387 A296521 * A184192 A263523 A133241
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 20 2013
STATUS
approved