OFFSET
1,15
COMMENTS
This sequence gives the number of ways to write n as n = a + a+3 + ... + a+3r = (r+1)(2a+3r)/2, with a and r integers > 0.
LINKS
Jean-Christophe Hervé, Table of n, a(n) for n = 1..10045
J. W. Andrushkiw, R. I. Andrushkiw and C. E. Corzatt, Representations of Positive Integers as Sums of Arithmetic Progressions, Mathematics Magazine, Vol. 49, No. 5 (Nov., 1976), pp. 245-248.
M. A. Nyblom and C. Evans, On the enumeration of partitions with summands in arithmetic progression, Australasian Journal of Combinatorics, Vol. 28 (2003), pp. 149-159.
FORMULA
EXAMPLE
a(15) = 2 because 15 = 6 + 9 = 2 + 5 + 8.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jean-Christophe Hervé, Jun 01 2014
STATUS
approved