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, 3, 16, 90, 504, 2849, 16224, 92988, 535840, 3101769, 18023856, 105076972, 614318040, 3600356175, 21146233920, 124436295054, 733493553408, 4330155834122, 25597817572320, 151508857016244, 897759260100648, 5325078489063039

Offset

0,2

Links

Table of n, a(n) for n=0..21.

Crossrefs

Cf. A026323.

Sequence in context: A356402 A347930 A026111 * A146963 A074562 A130744

Adjacent sequences: A026327 A026328 A026329 * A026331 A026332 A026333

Keyword

nonn

Author

Clark Kimberling

Status

approved