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A264273
Number of (2+1) X (n+1) arrays of permutations of 0..n*3+2 with each element having index change +-(.,.) 0,0 1,0 or 1,2.
1
9, 48, 256, 1280, 6400, 32000, 160000, 800000, 4000000, 20000000, 100000000, 500000000, 2500000000, 12500000000, 62500000000, 312500000000, 1562500000000, 7812500000000, 39062500000000, 195312500000000, 976562500000000
OFFSET
1,1
FORMULA
Empirical: a(n) = 5*a(n-1) for n>3.
Conjectures from Colin Barker, Jan 07 2019: (Start)
G.f.: x*(9 + 3*x + 16*x^2) / (1 - 5*x).
a(n) = 256*5^(n-3) for n>2.
(End)
EXAMPLE
Some solutions for n=4:
..7..1..9..8..4....5..8..9..3..4....5..1..2..3..4....7..1..2..3..4
.12.13..0..3..2....0.11..7..1..2....0.11..7.13..9....0.11.12..8.14
.10.11..5..6.14...10..6.12.13.14...10..6.12..8.14...10..6..5.13..9
CROSSREFS
Row 2 of A264272.
Sequence in context: A115053 A181959 A171011 * A226751 A073584 A007037
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 10 2015
STATUS
approved