A080330 Index in A002858 of the smaller of the two Ulam numbers that sum to the n-th Ulam number.

0, 0, 1, 1, 2, 2, 3, 2, 3, 2, 6, 2, 6, 2, 7, 1, 5, 4, 11, 9, 3, 6, 8, 10, 12, 2, 3, 4, 6, 18, 19, 13, 16, 3, 17, 20, 2, 3, 2, 24, 6, 11, 3, 8, 2, 15, 2, 3, 2, 15, 20, 2, 8, 27, 13, 25, 3, 6, 18, 2, 15, 2, 15, 25, 11, 6, 10, 2, 17, 3, 2, 15, 2, 3, 27, 20, 15, 20, 2, 25, 27, 42, 2, 15

Offset: 1

Author

Jud McCranie, Feb 15 2003

Keywords

• nonn

Comments

The first two are zero because the Ulam sequence (A002858) is initialized for those terms. The terms of the sum are in A080328 and A080329 and the indices are in A080330 and A080331.

Examples

			The 11th Ulam number (26) is the sum of the 6th Ulam number (8) and the 10th Ulam number (18), so a(11)=6.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Rémy Sigrist, PARI program for A080330

Crossrefs

Cf. A002858, A080328, A080329, A080331.

Programs

PARI

See Links section.