A160990 -id:A160990 - cp's OEIS frontend

A007690 Number of partitions of n in which no part occurs just once.

1, 0, 1, 1, 2, 1, 4, 2, 6, 5, 9, 7, 16, 11, 22, 20, 33, 28, 51, 42, 71, 66, 100, 92, 147, 131, 199, 193, 275, 263, 385, 364, 516, 511, 694, 686, 946, 925, 1246, 1260, 1650, 1663, 2194, 2202, 2857, 2928, 3721, 3813, 4866, 4967, 6257, 6487, 8051, 8342, 10369

Offset: 0

N. J. A. Sloane, Robert G. Wilson v

nonn

Also number of partitions of n into parts, each larger than 1, such that consecutive integers do not both appear as parts. Example: a(6)=4 because we have [6], [4,2], [3,3] and [2,2,2]. - Emeric Deutsch, Feb 16 2006
Also number of partitions of n into parts divisible by 2 or 3. - Alexander E. Holroyd (holroyd(AT)math.ubc.ca), May 28 2008
Infinite convolution product of [1,0,1,1,1,1,1] aerated n-1 times. i.e. [1,0,1,1,1,1,1] * [1,0,0,0,1,0,1] * [1,0,0,0,0,0,1] * ... . - Mats Granvik, Aug 07 2009

			a(6) = 4 because we have [3,3], [2,2,2], [2,2,1,1] and [1,1,1,1,1,1].
G.f. = 1 + x^2 + x^3 + 2*x^4 + x^5 + 4*x^6 + 2*x^7 + 6*x^8 + 5*x^9 + 9*x^10 + ...
G.f. = q + q^49 + q^73 + 2*q^97 + q^121 + 4*q^145 + 2*q^169 + 6*q^193 + ...

G. E. Andrews, Number Theory, Dover Publications, 1994. page 197. MR1298627
G. E. Andrews, The Theory of Partitions, Addison-Wesley, Reading, Mass., 1976, p. 14, Example 9.
I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983, (2.5.6).
R. Honsberger, Mathematical Gems III, M.A.A., 1985, p. 242.
P. A. MacMahon, Combinatory Analysis, Cambridge Univ. Press, London and New York, Vol. 1, 1915 and Vol. 2, 1916; see vol. 2, p 54, Article 300.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Alois P. Heinz, Table of n, a(n) for n = 0..10000
A. E. Holroyd, T. M. Liggett and D. Romik, Integrals, partitions and cellular automata, arXiv:math/0302216 [math.PR], 2003.
Eric Weisstein's World of Mathematics, Partition Function P

Cf. A000041, A055922, A055923, A114917, A114918, A183558, A183568.

Cf. A100405, A160974-A160990.

G:= mul((1-x^j+x^(2*j))/(1-x^j), j=1..70): Gser:=series(G, x, 60): seq(coeff(Gser, x, n), n=0..54); # Emeric Deutsch, Feb 10 2006

nn=40;CoefficientList[Series[Product[1/(1-x^i)-x^i,{i,1,nn}],{x,0,nn}],x] (* Geoffrey Critzer, Dec 02 2012 *)
a[ n_] := SeriesCoefficient[ QPochhammer[ x^6] / (QPochhammer[ x^2] QPochhammer[ x^3]), {x, 0, n}]; (* Michael Somos, Feb 22 2015 *)
nmax = 60; CoefficientList[Series[Product[(1 + x^(3*k))/(1 - x^(2*k)), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Sep 23 2015 *)
Table[Length@Select[Tally /@ IntegerPartitions@n, AllTrue[#, Last[#] > 1 &] &], {n, 0, 54}] (* Robert Price, Aug 17 2020 *)

{a(n) = my(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x^6 + A) / (eta(x^2 + A) * eta(x^3 + A)), n))}; /* Michael Somos, Apr 21 2004 */

G.f.: Product_{k>0 is a multiple of 2 or 3} (1/(1-x^k)). - Christian G. Bower, Jun 23 2000
G.f.: Product_{j>=1} (1+x^(3*j)) / (1-x^(2*j)). - Jon Perry, Mar 29 2004
Euler transform of period 6 sequence [0, 1, 1, 1, 0, 1, ...]. - Michael Somos, Apr 21 2004
G.f. is a period 1 Fourier series which satisfies f(-1 / (864 t)) = 1/6 (t/i)^(-1/2) g(t) where q = exp(2 Pi i t) and g(t) is the g.f. for A137566. - Michael Somos, Jan 26 2008
From Alois P. Heinz, Oct 09 2011: (Start)
a(n) = A000041(n) - A183558(n).
a(n) = A183568(n,0) - A183568(n,1).
G.f.: Product_{j>0} (1-x^j+x^(2*j)) / (1-x^j). (End)
a(n) ~ exp(2*Pi*sqrt(n)/3)/(6*sqrt(2)*n). - Vaclav Kotesovec, Sep 23 2015
a(n) = A000009(n/3) - Sum_{k>=1} (-1)^k a(n - k*(3*k +/- 1)). - Peter J. Taylor, May 16 2019

Minor edits by Vaclav Kotesovec, Aug 23 2015

A100405 Number of partitions of n where every part appears more than two times.

Original entry on oeis.org

1, 0, 0, 1, 1, 1, 2, 1, 2, 3, 3, 3, 7, 5, 6, 11, 10, 10, 17, 15, 20, 26, 25, 29, 44, 41, 47, 63, 67, 72, 99, 97, 114, 143, 148, 168, 216, 216, 248, 306, 328, 358, 443, 462, 527, 629, 665, 739, 898, 936, 1055, 1238, 1330, 1465, 1727, 1837, 2055, 2366, 2543, 2808, 3274

Offset: 0

Vladeta Jovovic, Jan 11 2005

			a(6)=2 because we have [2,2,2] and [1,1,1,1,1,1].

Alois P. Heinz, Table of n, a(n) for n = 0..10000 (terms n = 1..5000 from Vaclav Kotesovec)

Cf. A007690, A160974-A160990.
Cf. A266647, A266648, A266649, A266650.
Cf. A161294.

G:=product((1+x^(3*k)/(1-x^k)),k=1..30): Gser:=series(G,x=0,80): seq(coeff(Gser,x,n),n=0..70); # Emeric Deutsch, Aug 06 2005
# second Maple program:
b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
      add(b(n-i*j, i-1), j=[0, $3..iquo(n, i)])))
    end:
a:= n-> b(n$2):
seq(a(n), n=0..70);  # Alois P. Heinz, Aug 20 2019

nmax = 100; Rest[CoefficientList[Series[Product[1 + x^(3*k)/(1-x^k), {k, 1, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Nov 28 2015 *)

G.f.: Product_{k>0} (1+x^(3*k)/(1-x^k)). More generally, g.f. for number of partitions of n where every part appears more than m times is Product_{k>0} (1+x^((m+1)*k)/(1-x^k)).

a(n) ~ sqrt(Pi^2 + 6*c) * exp(sqrt((2*Pi^2/3 + 4*c)*n)) / (4*sqrt(3)*Pi*n), where c = Integral_{0..infinity} log(1 - exp(-x) + exp(-3*x)) dx = -0.77271248407593487127235205445116662610863126869049971822566... . - Vaclav Kotesovec, Jan 05 2016

More terms from Emeric Deutsch, Aug 06 2005

a(0)=1 prepended by Alois P. Heinz, Aug 20 2019

A160974 Number of partitions of n where every part appears at least 4 times.

Original entry on oeis.org

1, 0, 0, 0, 1, 1, 1, 1, 2, 1, 2, 1, 4, 2, 4, 4, 7, 5, 8, 7, 13, 10, 13, 12, 21, 18, 22, 21, 34, 29, 40, 36, 55, 48, 63, 64, 88, 79, 100, 99, 139, 125, 160, 155, 207, 199, 241, 241, 314, 302, 369, 366, 466, 454, 550, 557, 690, 679, 807, 821, 1016, 1001, 1180, 1207, 1460, 1466, 1708

Offset: 0

R. H. Hardin, Jun 01 2009

nonn

			a(12) = 4 because we have 3333, 2^6, 22221111, and 1^(12). - _Emeric Deutsch_, Jun 24 2009

Alois P. Heinz, Table of n, a(n) for n = 0..10000 (terms n=1..967 from R. H. Hardin)

Cf. A007690, A100405, A160975-A160990.

g := product(1+x^(4*j)/(1-x^j), j = 1..30): gser := series(g, x = 0, 85): seq(coeff(gser, x, n), n = 0..66); # Emeric Deutsch, Jun 24 2009
# second Maple program:
b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
      add(b(n-i*j, i-1), j=[0, $4..iquo(n, i)])))
    end:
a:= n-> b(n$2):
seq(a(n), n=0..80);  # Alois P. Heinz, Oct 02 2017

nmax = 100; CoefficientList[Series[Product[1 + x^(4*k)/(1-x^k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Nov 28 2015; offset adapted by Georg Fischer, Sep 18 2020 *)

G.f.: Product_{j>=1} (1+x^(4*j)/(1-x^j)). - Emeric Deutsch, Jun 24 2009

a(n) ~ sqrt(Pi^2 + 6*c) * exp(sqrt((2*Pi^2/3 + 4*c)*n)) / (4*sqrt(3)*Pi*n), where c = Integral_{0..infinity} log(1 - exp(-x) + exp(-4*x)) dx = -0.903005550655893892139378653023287247062261773608753265529... . - Vaclav Kotesovec, Jan 05 2016

Initial terms changed to match b-file. - N. J. A. Sloane, Aug 31 2009
Maple program fixed by Vaclav Kotesovec, Nov 28 2015
a(0)=1 prepended by Alois P. Heinz, Oct 02 2017

A160975 Number of partitions of n where every part appears at least 5 times.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 3, 3, 3, 5, 4, 7, 7, 7, 8, 11, 12, 12, 14, 15, 16, 23, 20, 24, 26, 29, 36, 40, 40, 46, 50, 63, 63, 76, 76, 87, 103, 108, 117, 135, 140, 167, 173, 191, 205, 235, 257, 278, 300, 327, 354, 413, 424, 469, 511, 555, 616, 673, 711, 783, 849, 947

Offset: 0

R. H. Hardin, Jun 01 2009

nonn

			a(15) = 3 because we have 33333, 2222211111, and 1^(15). - _Emeric Deutsch_, Jun 28 2009

Seiichi Manyama, Table of n, a(n) for n = 0..5000 (terms 1..1000 from R. H. Hardin)

Cf. A007690, A100405, A160974, A160976-A160990.

g := product(1+x^(5*j)/(1-x^j), j = 1..20): gser := series(g, x = 0, 80): seq(coeff(gser, x, n), n = 0..75); # Emeric Deutsch, Jun 28 2009
# second Maple program:
b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
      b(n, i-1)+add(b(n-i*j, i-1), j=5..n/i)))
    end:
a:= n-> b(n$2):
seq(a(n), n=0..70);  # Alois P. Heinz, Feb 06 2024

nmax = 100; Rest[CoefficientList[Series[Product[1 + x^(5*k)/(1-x^k), {k, 1, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Nov 28 2015 *)

G.f.: Product_{j>=1} (1+x^(5*j)/(1-x^j)). - Emeric Deutsch, Jun 28 2009

a(n) ~ sqrt(Pi^2 + 6*c) * exp(sqrt((2*Pi^2/3 + 4*c)*n)) / (4*sqrt(3)*Pi*n), where c = Integral_{0..infinity} log(1 - exp(-x) + exp(-5*x)) dx = -0.990807844177842472956484606320623872921836802804155824925... . - Vaclav Kotesovec, Jan 05 2016

Initial terms changed to match b-file. - N. J. A. Sloane, Aug 31 2009
Maple program fixed by Vaclav Kotesovec, Nov 28 2015
a(0)=1 prepended by Seiichi Manyama, Feb 06 2024

cp's OEIS Frontend

A007690 Number of partitions of n in which no part occurs just once.

Views

Author

Keywords

Comments

Examples

References

Links

Crossrefs

Programs

Maple

Mathematica

PARI

Formula

Extensions

A100405 Number of partitions of n where every part appears more than two times.

Views

Author

Keywords

Examples

Links

Crossrefs

Programs

Maple

Mathematica

Formula

Extensions

A160974 Number of partitions of n where every part appears at least 4 times.

Views

Author

Keywords

Examples

Links

Crossrefs

Programs

Maple

Mathematica

Formula

Extensions

A160975 Number of partitions of n where every part appears at least 5 times.

Views

Author

Keywords

Examples

Links

Crossrefs

Programs

Maple

Mathematica

Formula

Extensions