A129878 Sequence a_n arising in enumeration of arrays of directed blocks (see Quaintance reference for precise definition).

1, 3, 10, 42, 178, 787, 3552, 16319, 76032, 358394, 1706251, 8193321, 39641852, 193085107, 946088197, 4660551304, 23069512548, 114693318822, 572485658453, 2867920198436, 14414924060475, 72674575668147, 367428218847702, 1862467167450794, 9463393569051636, 48191664539220483

Offset

1,2

Links

Table of n, a(n) for n=1..26.

Jocelyn Quaintance, Letter Representations of m x n x p Proper Arrays, arXiv:math/0412244 [math.CO], 2004-2006. See Table 1.

Jocelyn Quaintance, Combinatoric Enumeration of Two-Dimensional Proper Arrays, Discrete Math., 307 (2007), 1844-1864. See Table 1.

Formula

See Quaintance reference for generating functions that produce A129872-A129886.

a(n) = A129876(n) - A129880(n). - Thomas Scheuerle, Jan 14 2026

Crossrefs

Cf. A129873-A129886.

Sequence in context: A370537 A214835 A149059 * A094558 A074511 A000249

Adjacent sequences: A129875 A129876 A129877 * A129879 A129880 A129881

Keyword

nonn

Author

N. J. A. Sloane, May 26 2007

Extensions

More terms from Thomas Scheuerle, Jan 14 2026

Status

approved