A180221 Numbers that can be written as sum of one or more distinct elements of A000043. Numbers k for which sigma(A180162(k))=2^k, k>=2.

2, 3, 5, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75

Offset

1,1

Comments

The distinct values of log_2(sigma(m)), where m > 1 is a term of A046528. - Amiram Eldar, Jun 02 2020

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1855 from Walter A. Kehowski)

Mathematica

n = 10; p = MersennePrimeExponent[Range[n]]; Rest[-1 + Position[CoefficientList[Series[Product[(1 + x^p[[k]]), {k, 1, n}], {x, 0, p[[-1]]}], x], _?(# > 0 &)] // Flatten] (* Amiram Eldar, Jun 02 2020 *)

Crossrefs

Cf. A000043, A180162, A046528, A180169. Complement of A078426.

Sequence in context: A357065 A039072 A055977 * A111292 A047373 A039048

Adjacent sequences: A180218 A180219 A180220 * A180222 A180223 A180224

Keyword

nonn

Author

Walter Kehowski, Aug 16 2010

Status

approved