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A180908
Number of sequences of n integers p(i) i=0..n-1 with 0<=p(i)<=3*i and -3<p(i)-p(i-1)<=3
1
1, 4, 21, 116, 659, 3802, 22146, 129838, 764731, 4519504, 26778943, 158989206, 945437948, 5629314106, 33553133752, 200164459648, 1194964743750, 7138188267650, 42662447719844, 255091414376360, 1525848441256765
OFFSET
1,2
COMMENTS
Paths down a n-high staggered-grid minimally right-leaning right triangle with interior neighbor fanout 2*3
Column 3 of A180915
LINKS
CROSSREFS
Sequence in context: A255139 A015554 A024051 * A212419 A020048 A318365
KEYWORD
nonn
AUTHOR
R. H. Hardin Sep 23 2010
STATUS
approved