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!)
A200476 Number of partitions of n such that the number of parts and the largest part and the smallest part are pairwise not coprime. 2
0, 0, 0, 1, 0, 1, 0, 3, 1, 3, 1, 8, 3, 9, 6, 16, 9, 24, 17, 35, 29, 49, 45, 81, 73, 110, 115, 166, 166, 240, 250, 347, 372, 491, 539, 715, 776, 988, 1109, 1393, 1553, 1935, 2178, 2676, 3034, 3674, 4176, 5056, 5734, 6862, 7834, 9316, 10615, 12576, 14341, 16890 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

COMMENTS

See comments in A199891, which apply to this sequence also.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..300

EXAMPLE

a(8)  = 3: [2,6], [4,4], [2,2,2,2];

a(9)  = 1: [3,3,3];

a(10) = 3: [2,8], [4,6], [2,2,2,4];

a(11) = 1: [2,2,3,4];

a(12) = 8: [2,10], [4,8], [6,6], [3,3,6], [2,2,2,6], [2,2,4,4], [2,3,3,4], [2,2,2,2,2,2].

MAPLE

b:= proc(n, j, t, k) option remember;

      add(b(n-i, i, t+1, k), i=j..iquo(n, 2))+

      `if`(igcd(n, t)>1 and igcd(k, t)>1 and igcd(n, k)>1, 1, 0)

    end:

a:= n-> add(b(n-j, j, 2, j), j=2..iquo(n, 2)):

seq(a(n), n=1..70);

MATHEMATICA

b[n_, j_, t_, k_] := b[n, j, t, k] = Sum[b[n-i, i, t+1, k], {i, j, Quotient[n, 2]}] + If[GCD[n, t]>1 && GCD[k, t]>1 && GCD[n, k]>1, 1, 0]; a[n_] := Sum [b[n-j, j, 2, j], {j, 2, Quotient[n, 2]}]; Table[a[n], {n, 1, 70}] (* Jean-François Alcover, Feb 06 2017, translated from Maple *)

CROSSREFS

Cf. A199891.

Sequence in context: A122410 A309790 A082495 * A300251 A016572 A072860

Adjacent sequences:  A200473 A200474 A200475 * A200477 A200478 A200479

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Nov 18 2011

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 April 5 08:42 EDT 2020. Contains 333238 sequences. (Running on oeis4.)