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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A079125 Number of ways to partition the sum of all divisors of n (sigma(n), A000203) into distinct positive integers not greater than n. 4
1, 1, 1, 2, 3, 5, 5, 13, 13, 27, 14, 89, 21, 89, 97, 230, 45, 613, 63, 980, 347, 580, 121, 6663, 330, 1289, 1043, 5847, 295, 26488, 389, 12813, 2800, 5411, 2840, 156304, 863, 10433, 6939, 161711, 1425, 272499, 1815, 103738, 61469, 35448, 2909, 2475011 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..48.

FORMULA

a(n) = b(0, n), b(m, n) = 1 + sum(b(i, j): m<i<j<n & i+j=sigma(n)).

PROG

(PARI) a(n)=my(v=partitions(sigma(n), n)); sum(i=1, #v, #vecsort(v[i], , 8)==#v[i]) \\ Charles R Greathouse IV, Feb 14 2013

CROSSREFS

Cf. A079126, A000009, A079122, A079124, A067953.

Sequence in context: A342421 A319631 A097453 * A146305 A342437 A079022

Adjacent sequences:  A079122 A079123 A079124 * A079126 A079127 A079128

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Dec 27 2002

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 25 14:37 EDT 2021. Contains 347654 sequences. (Running on oeis4.)