login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A252891 Numbers n such that sigma(n) is a partition number. 2
1, 2, 4, 8, 20, 26, 28, 29, 39, 41, 129, 430, 526, 591, 655, 731, 1388, 1622, 2249, 3734, 6841, 18752, 18772, 21332, 35017, 37337, 53173, 105557, 113377, 124753, 419029, 614153, 824149, 829333, 2192923, 2369654, 2538915, 3059853, 3388115, 3479244, 3557183 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Robert G. Wilson v, Table of n, a(n) for n = 1..65

EXAMPLE

26 is in the sequence because the sum of divisors of 26 is 1 + 2 + 13 + 26 = 42 and 42 is a partition number because the number of partitions of 10 is equal to 42.

MATHEMATICA

(* To extend the search beyond 50400, be sure to increase the length of partNums accordingly *) partNums = PartionsP[Range[50]]; Select[Range[100], MemberQ[partNums, DivisorSigma[1, #]] &] (* Alonso del Arte, Dec 24 2014 *)

CROSSREFS

Cf. A000041, A000203.

Sequence in context: A124154 A296606 A222562 * A102634 A026520 A282983

Adjacent sequences:  A252888 A252889 A252890 * A252892 A252893 A252894

KEYWORD

nonn

AUTHOR

Omar E. Pol, Dec 24 2014

EXTENSIONS

a(11)-a(16) from Alonso del Arte, Dec 24 2014

More terms from Michel Marcus, Dec 27 2014

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 June 19 19:11 EDT 2019. Contains 324222 sequences. (Running on oeis4.)