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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A085491 Number of ways to write n as sum of distinct divisors of n+1. 5
1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 2, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 5, 0, 0, 0, 1, 0, 3, 0, 1, 0, 0, 0, 5, 0, 0, 0, 3, 0, 2, 0, 0, 0, 0, 0, 10, 0, 0, 0, 0, 0, 1, 0, 2, 0, 0, 0, 31, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 26, 0, 0, 0, 0, 0, 1, 0, 6, 0, 0, 0, 23, 0, 0, 0, 1, 0, 20, 0, 0, 0, 0, 0, 21, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,12

COMMENTS

a(A085492(n)) = 0; a(A085493(n)) > 0; a(A085494(n)) = 1.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..10000

EXAMPLE

n=11, divisors of 12=11+1 that are not greater 11: {1,2,3,4,6}, 11=6+5=6+4+1, therefore a(11)=2.

MAPLE

a:= proc(m) option remember; local b, l; b, l:=

      proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,

        b(n, i-1)+`if`(l[i]>n, 0, b(n-l[i], i-1))))

      end, sort([numtheory[divisors](m+1)[]]);

      forget(b); b(m, nops(l)-1)

    end:

seq(a(n), n=0..120);  # Alois P. Heinz, Mar 12 2019

MATHEMATICA

a[n_] := Module[{dd}, dd = Select[Divisors[n+1], # <= n&]; Select[ IntegerPartitions[n, dd // Length, dd], Reverse[#] == Union[#]&] // Length]; Array[a, 100, 0] (* Jean-Fran├žois Alcover, Mar 12 2019 *)

CROSSREFS

Cf. A085496.

Sequence in context: A280751 A280749 A321936 * A321013 A284258 A322389

Adjacent sequences:  A085488 A085489 A085490 * A085492 A085493 A085494

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jul 03 2003

EXTENSIONS

a(0)=1 prepended by Alois P. Heinz, Mar 12 2019

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 December 12 22:06 EST 2019. Contains 329963 sequences. (Running on oeis4.)