A183528 An Ulam-type sequence: a(n) = n if n<=5; for n>5, a(n) = least number > a(n-1) which is a unique sum of 5 distinct earlier terms.

1, 2, 3, 4, 5, 15, 25, 26, 27, 28, 29, 35, 43, 45, 165, 171, 172, 174, 180, 181, 328, 333, 338, 339, 340, 341, 493, 499, 500, 647, 652, 657, 658, 659, 660, 661, 662, 663, 815, 818, 819, 971, 1127, 1137, 1138, 1139, 1140, 1141, 1142

Offset

1,2

Comments

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

Links

Alois P. Heinz, Table of n, a(n) for n = 1..1000

Index entries for Ulam numbers

Example

a(6) = 15 = 1 + 2 + 3 + 4 + 5 = 5*6/2, because it is the least number >5 with a unique sum of 5 distinct earlier terms.
a(7) = 25 = 1 + 2 + 3 + 4 + 15 = 5^2, because it is the least number >15 with a unique sum of 5 distinct earlier terms.

Maple

# see A183534 for programs.

Crossrefs

Column k=5 of A183534.

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

Sequence in context: A227535 A096774 A201356 * A145029 A145030 A242948

Adjacent sequences: A183525 A183526 A183527 * A183529 A183530 A183531

Keyword

nonn

Author

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

Status

approved