A183530 An Ulam-type sequence: a(n) = n if n<=7; for n>7, a(n) = least number > a(n-1) which is a unique sum of 7 distinct earlier terms.

1, 2, 3, 4, 5, 6, 7, 28, 49, 50, 51, 52, 53, 54, 55, 70, 82, 91, 109, 112, 555, 556, 563, 564, 572, 573, 576, 583, 584, 591, 593, 1103, 1104, 1105, 1111, 1112, 1124, 1632, 1637, 1642, 1643, 1648, 1653, 1654, 1655, 1656, 1657, 1660, 1661, 1662, 1671, 1672, 2184

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..500

Index entries for Ulam numbers

Example

a(8) = 28 = 1 + ... + 7 = 7*8/2, because it is the least number >7 with a unique sum of 7 distinct earlier terms.
a(9) = 49 = 1 + ... + 6 + 28 = 7^2, because it is the least number >28 with a unique sum of 7 distinct earlier terms.

Maple

# see A183534 for programs.

Crossrefs

Column k=7 of A183534.

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

Sequence in context: A153687 A142594 A010351 * A173576 A364154 A024645

Adjacent sequences: A183527 A183528 A183529 * A183531 A183532 A183533

Keyword

nonn

Author

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

Status

approved