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

Author

Leroy Quet, May 03 2006

Keywords

• easy
• nonn

Programs

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 *)

Extensions

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