A118551 a(0)=1. a(n) = a(n-1)*2, if n is in the sequence. a(n) = a(n-1) + 1 if n is missing from the sequence.

1, 2, 4, 5, 10, 20, 21, 22, 23, 24, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 114, 228, 456, 912, 1824, 1825, 1826, 1827, 1828, 1829, 1830, 1831, 1832, 1833, 1834, 1835, 1836, 1837, 1838, 1839, 1840, 1841, 1842, 1843, 1844, 1845, 1846, 1847, 3694, 7388, 14776

Offset

0,2

Links

Table of n, a(n) for n=0..50.

Mathematica

f[s_] := Block[{n = Length@s}, Append[s, If[ MemberQ[s, n], 2s[[ -1]], s[[ -1]] + 1]]]; Nest[f, {1}, 50] (* Robert G. Wilson v, May 16 2006 *)

Crossrefs

Sequence in context: A000675 A005018 A249399 * A161706 A128401 A018467

Adjacent sequences: A118548 A118549 A118550 * A118552 A118553 A118554

Keyword

easy,nonn

Author

Leroy Quet, May 03 2006

Extensions

More terms from Robert G. Wilson v, May 16 2006

Status

approved