A080571 Number of 2's in partition of n-th Ulam number into sum of two distinct Ulam numbers.

0, 1, 1, 1, 2, 3, 4, 5, 6, 7, 10, 11, 14, 15, 18, 18, 20, 21, 24, 26, 27, 29, 31, 33, 37, 38, 39, 40, 43, 47, 50, 53, 55, 56, 59, 66, 67, 68, 69, 72, 75, 78, 79, 83, 84, 90, 91, 92, 93, 96, 98, 99, 104, 107, 118, 120, 121, 123, 128, 129, 136, 137, 138, 141, 146, 149, 153, 154

Offset: 1

Author

Naohiro Nomoto, Feb 22 2003

Keywords

• easy
• nonn

Examples

			For n=7: A002858(7) = 11 = 3+8 = (1+2)+(2+6) = (1+2)+(2+(2+4)) = (1+2)+(2+(2+(1+3))) = (1+2)+(2+(2+(1+(1+2)))). Number of 2's in (1+2)+(2+(2+(1+(1+2)))) is 4, so a(7) = 4.
		

Crossrefs

Cf. A002858.