The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A084978 Number of ways to represent n as a+b*(c+d*(e+f*(...x+y*(z)...))) in positive integers. 0
 1, 2, 5, 11, 25, 51, 110, 221, 456, 918, 1864, 3729, 7528, 15057, 30227, 60485, 121205, 242411, 485337, 970675, 1942307, 3884730, 7771327, 15542655, 31089330, 62178686, 124364903, 248730268, 497475717, 994951435, 1989934099, 3979868199 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA a(n+1) = Sum(k=1..n; Sum(d|k; a(d)). a(n+1) = 1 + Sum(k=1..n; Sum(d|k; a(d)) or a(n+1) = a(n) + Sum(d|n; a(d)). - Vladeta Jovovic, Aug 08 2004 G.f. A(x) satisfies: A(x) = (x/(1 - x)) * (1 + Sum_{k>=1} A(x^k)). - Ilya Gutkovskiy, Feb 25 2020 EXAMPLE a(3) = 5: 3 = 2+1(1) = 1+2(1) = 1+1(2) = 1+1(1+1(1)). CROSSREFS Sequence in context: A134527 A124379 A302830 * A118036 A291552 A208739 Adjacent sequences:  A084975 A084976 A084977 * A084979 A084980 A084981 KEYWORD nonn AUTHOR David W. Wilson, Jun 16 2003 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 23 10:07 EDT 2021. Contains 343204 sequences. (Running on oeis4.)