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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A171634 Number of compositions of n such that the number of parts is divisible by the greatest part. 2
1, 1, 3, 2, 8, 13, 21, 38, 89, 173, 302, 545, 1109, 2309, 4564, 8601, 16188, 31365, 62518, 125813, 251119, 493123, 956437, 1854281, 3633938, 7218166, 14444539, 28868203, 57300450, 112921744, 221760513, 436117749, 861764899, 1711773936 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 1..715 (terms 1..250 from Alois P. Heinz)

FORMULA

G.f.: Sum_{n>=0} Sum_{d|n} ((x^(d+1)-x)^n-(x^d-x)^n)/(x-1)^n.

MAPLE

b:= proc(n, t, g) option remember; `if`(n=0, `if`(irem(t, g)=0, 1, 0), add(b(n-i, t+1, max(i, g)), i=1..n)) end: a:= n-> b(n, 0, 0): seq(a(n), n=1..40); # Alois P. Heinz, Dec 15 2009

MATHEMATICA

b[n_, t_, g_] := b[n, t, g] = If[n == 0, If [Mod[t, g] == 0, 1, 0], Sum[b[n - i, t + 1, Max[i, g]], {i, 1, n}]];

a[n_] := b[n, 0, 0];

Array[a, 40] (* Jean-Fran├žois Alcover, Nov 11 2020, after Alois P. Heinz *)

CROSSREFS

Cf. A168659, A171632.

Sequence in context: A088551 A301903 A165660 * A107300 A285787 A047946

Adjacent sequences:  A171631 A171632 A171633 * A171635 A171636 A171637

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic, Dec 13 2009

EXTENSIONS

More terms from Alois P. Heinz, Dec 15 2009

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 2 10:39 EST 2020. Contains 338876 sequences. (Running on oeis4.)