A084083 Length of lists created by n substitutions k -> range(k+1, -abs(k), -2) starting with {1}.

1, 2, 4, 9, 19, 44, 96, 227, 507, 1218, 2768, 6732, 15504, 38076, 88616, 219351, 514855, 1282710, 3031860, 7594665, 18056415, 45439056, 108570432, 274299284, 658208244, 1668646424, 4018977888, 10219252296, 24693586436

Offset

0,2

Links

Table of n, a(n) for n=0..28.

Example

{1}, {2,0}, {3,1,-1,1}, {4,2,0,-2,2,0,0,2,0} have lengths 1, 2, 4, 9.

Mathematica

Length/@Flatten/@NestList[ # /. k_Integer:>Range[k+1, -Abs[k], -2]&, {1}, 16]

Crossrefs

Sequence in context: A339156 A383894 A247623 * A036611 A316473 A316501

Adjacent sequences: A084080 A084081 A084082 * A084084 A084085 A084086

Keyword

nonn,more

Author

Wouter Meeussen, May 11 2003

Extensions

a(17)-a(19) from Robert G. Wilson v, Aug 17 2009

a(20)-a(28) from Sean A. Irvine, Mar 10 2026

Status

approved