A079790 a(n) = number of m <= n which can be obtained by deleting digits from n.

1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 4, 5, 6, 6, 6, 6

Offset: 1

Author

Amarnath Murthy, Feb 04 2003

Keywords

• base
• easy
• nonn

Comments

a(n) = A120004(n) for n <= 100. a(101) = #{0, 1, 10, 11, 101} = 5; a(102) = #{0, 1, 2, 10, 12, 102} = 6. - Reinhard Zumkeller, Jun 15 2006

Examples

			a(124)=7 and the numbers are 1,2,4,12,14,24,124.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Programs

Maple

f:= proc(n) local L,V;
  L:= convert(n,base,10);
  V:= convert(map(t -> L[t], combinat:-powerset([$1..nops(L)])),set) minus {[]};
  V:= map(proc(t) local i; add(t[i]*10^(i-1),i=1..nops(t)) end proc,V);
  nops(select(t -> t <= n, V))
end proc:
map(f, [$1..100]); # Robert Israel, Dec 03 2024

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 19 2003

Corrected and extended by Reinhard Zumkeller, Jun 15 2006