A064531 Number of connected components remaining when decimal expansion of the number n is cut from a piece of paper.

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

Offset: 0

Author

N. J. A. Sloane, Oct 07 2001

Keywords

• nonn
• easy
• base

Comments

Assumes that 4 is represented without a hole.

Crossrefs

Cf. A064529, A064530. Equals A064532 + 1.

Programs

Mathematica

a[n_ /; 0 <= n <= 9] := a[n] = {2, 1, 1, 1, 1, 1, 2, 1, 3, 2}[[n + 1]]; a[n_] := Total[a /@ (id = IntegerDigits[n])] - Length[id] + 1 ; Table[a[n], {n, 0, 104}] (* Jean-François Alcover, Nov 22 2013 *)

Extensions

More terms from Matthew Conroy, Oct 09 2001