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A026330
a(n) = number of (s(0), s(1), ..., s(n)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| <= 1 for i = 1,2,...,n, s(0) = 2, s(2n) = n+1. Also a(n) = T(2n,n+1), where T is the array in A026323.
0
0, 3, 16, 90, 504, 2849, 16224, 92988, 535840, 3101769, 18023856, 105076972, 614318040, 3600356175, 21146233920, 124436295054, 733493553408, 4330155834122, 25597817572320, 151508857016244, 897759260100648, 5325078489063039
OFFSET
0,2
CROSSREFS
Cf. A026323.
Sequence in context: A356402 A347930 A026111 * A146963 A074562 A130744
KEYWORD
nonn
STATUS
approved