A183529 An Ulam-type sequence: a(n) = n if n<=6; for n>6, a(n) = least number > a(n-1) which is a unique sum of 6 distinct earlier terms.

1, 2, 3, 4, 5, 6, 21, 36, 37, 38, 39, 40, 41, 51, 61, 66, 284, 285, 289, 290, 297, 298, 299, 310, 312, 559, 561, 562, 570, 571, 574, 575, 834, 836, 837, 838, 839, 840, 841, 849, 850, 1109, 1124, 1125, 1126, 1127, 1386, 1401, 1402, 1661, 1676, 1677, 1936, 1951

Offset: 1

Author

Jonathan Vos Post and Alois P. Heinz, Jan 05 2011

Keywords

• nonn

Comments

An Ulam-type sequence - see A002858 for further information.

Examples

			a(7) = 21 = 1 + ... + 6 = 6*7/2, because it is the least number >6 with a unique sum of 6 distinct earlier terms.
a(8) = 36 = 1 + ... + 5 + 21 = 6^2, because it is the least number >21 with a unique sum of 6 distinct earlier terms.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..700
• Index entries for Ulam numbers

Crossrefs

Column k=6 of A183534.

Cf. A002858, A007086, A183527-A183533, A135737.

Programs

Maple

# see A183534 for programs.