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

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A201025 Number of partitions of n such that the number of parts and the smallest part are not coprime. 3
0, 0, 0, 1, 1, 1, 1, 3, 4, 5, 7, 10, 12, 15, 18, 25, 30, 39, 47, 62, 74, 94, 113, 144, 173, 215, 261, 324, 390, 476, 571, 697, 832, 1004, 1196, 1439, 1706, 2038, 2409, 2868, 3380, 4001, 4702, 5550, 6504, 7645, 8938, 10478, 12218, 14277, 16612, 19363, 22481 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..400

FORMULA

a(n) = A000041(n) - A200928(n).

EXAMPLE

a(7) = 1: [2,5];

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

a(9) = 4: [2,2,2,3], [3,3,3], [4,5], [2,7];

a(10) = 5: [2,2,3,3], [2,2,2,4], [3,3,4], [4,6], [2,8];

a(11) = 7: [2,3,3,3], [2,2,3,4], [3,4,4], [2,2,2,5], [3,3,5], [4,7], [2,9].

MAPLE

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

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

      `if`(igcd(t, s)>1, 1, 0)

    end:

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

seq (a(n), n=1..60);

MATHEMATICA

b[n_, j_, t_, s_] := b[n, j, t, s] = Sum[b[n-i, i, Mod[t+1, s], s], {i, j, Quotient[n, 2]}] + If[GCD[t, s]>1, 1, 0]; a[n_] := Sum [b[n-i, i, 2, i], {i, 2, Quotient[n, 2]}]; Table[a[n], {n, 1, 60}] (* Jean-Fran├žois Alcover, Feb 15 2017, translated from Maple *)

CROSSREFS

Cf. A000041, A199889, A200928.

Sequence in context: A159560 A288427 A030502 * A288451 A236384 A073957

Adjacent sequences:  A201022 A201023 A201024 * A201026 A201027 A201028

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Nov 25 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 January 20 14:02 EST 2020. Contains 331094 sequences. (Running on oeis4.)