cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Previous Showing 11-20 of 27 results. Next

A002622 Number of partitions of at most n into at most 5 parts.

Original entry on oeis.org

1, 2, 4, 7, 12, 19, 29, 42, 60, 83, 113, 150, 197, 254, 324, 408, 509, 628, 769, 933, 1125, 1346, 1601, 1892, 2225, 2602, 3029, 3509, 4049, 4652, 5326, 6074, 6905, 7823, 8837, 9952, 11178, 12520, 13989, 15591, 17338, 19236, 21298, 23531, 25949, 28560, 31378, 34412
Offset: 0

Views

Author

Keywords

Examples

			G.f. = 1 + 2*x + 4*x^2 + 7*x^3 + 12*x^4 + 19*x^5 + 29*x^6 + 42*x^7 + 60*x^8 + ...
a(2) = 4 with partitions 0, 1, 2, 1+1. a(3) = 7 with partitions 0, 1, 2, 1+1, 3, 2+1, 1+1+1. - _Michael Somos_, Apr 24 2014
		

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A001401 (first differences). Column 5 of A092905.

Programs

  • Mathematica
    CoefficientList[Series[1/((1 - x)^2 (1 - x^2) (1 - x^3) (1 - x^4) (1 - x^5)), {x, 0, 100}], x] (* Vincenzo Librandi, Apr 25 2014 *)
    LinearRecurrence[{2, 0, -1, 0, -1, 0, 0, 2, 0, 0, -1, 0, -1, 0, 2, -1},  {1, 2, 4, 7, 12, 19, 29, 42, 60, 83, 113, 150, 197, 254, 324, 408},  48] (* Georg Fischer, Feb 27 2019 *)
  • PARI
    x='x+O('x^99); Vec(1/((1-x)*prod(i=1, 5, 1-x^i))) \\ Altug Alkan, Mar 30 2018

Formula

G.f.: 1/[(1+x^2)*(1-x^3)*(1-x)^4*(1-x^5)*(1+x)^2]. (Corrected Mar 31 2018)
a(n)= 2*a(n-1) -a(n-3) -a(n-5) +2*a(n-8) -a(n-11) -a(n-13) +2*a(n-15) -a(n-16).
G.f.: 1 / ((1 - x)^2 * (1 - x^2) * (1 - x^3) * (1 - x^4) * (1 - x^5)). - Michael Somos, Apr 24 2014
Euler transform of length 5 sequence [ 2, 1, 1, 1, 1]. - Michael Somos, Apr 24 2014
a(n) = a(n-1) + A001401(n). - Michael Somos, Apr 24 2014
a(n) = round((n+1)*(6*n^4+234*n^3+3326*n^2+20674*n+50651+675*(-1)^n)/86400). - Tani Akinari, May 05 2014

A103924 Number of partitions of n into parts but with two kinds of parts of sizes 1,2,3,4 and 5.

Original entry on oeis.org

1, 2, 5, 10, 20, 36, 64, 107, 177, 282, 443, 678, 1026, 1522, 2234, 3231, 4628, 6550, 9193, 12774, 17619, 24098, 32740, 44161, 59213, 78894, 104553, 137787, 180702, 235806, 306354, 396226, 510392, 654787, 836911, 1065734, 1352475, 1710535, 2156536, 2710318
Offset: 0

Views

Author

Wolfdieter Lang, Mar 24 2005

Keywords

Comments

See A103923 for other combinatorial interpretations of a(n).
Convolution of A001401 and A000041. - Vaclav Kotesovec, Aug 28 2015
Also the sum of binomial (D(p), 5) over partitions p of n+15, where D(p) is the number of different part sizes in p. - Emily Anible, Jun 09 2018

References

  • H. Gupta et al., Tables of Partitions. Royal Society Mathematical Tables, Vol. 4, Cambridge Univ. Press, 1958 (reprinted 1962), p. 90.
  • J. Riordan, Combinatorial Identities, Wiley, 1968, p. 199.

Crossrefs

Sixth column (m=5) of Fine-Riordan triangle A008951 and of triangle A103923, i.e. the p_2(n, m) array of the Gupta et al. reference.
Cf. A000712 (all parts of two kinds).

Programs

  • Maple
    with(numtheory): a:= proc(n) a(n):=`if`(n=0, 1, add(add(d*`if`(d<6, 2, 1), d=divisors(j)) *a(n-j), j=1..n)/n) end: seq(a(n), n=0..40); # Alois P. Heinz, Sep 14 2014
  • Mathematica
    a[n_] := a[n] = If[n==0, 1, Sum[Sum[d*If[d<6, 2, 1], {d, Divisors[j]}] * a[n-j], {j, 1, n}]/n]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Aug 28 2015, after Alois P. Heinz *)
    nmax=60; CoefficientList[Series[Product[1/(1-x^k), {k, 1, 5}] * Product[1/(1-x^k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 28 2015 *)
    Table[Length@IntegerPartitions[n, All, Range@n~Join~Range@5],  {n,0,39}] (* Robert Price, Jul 29 2020 *)
    T[n_, 0] := PartitionsP[n];
    T[n_, m_] /; (n >= m(m+1)/2) := T[n, m] = T[n-m, m-1] + T[n-m, m];
    T[, ] = 0;
    a[n_] := T[n+15, 5];
    Table[a[n], {n, 0, 60}] (* Jean-François Alcover, May 30 2021 *)

Formula

G.f.: (product(1/(1-x^k), k=1..5)^2)*product(1/(1-x^j), j=6..infty).
a(n) = sum(A000710(n-5*j), j=0..floor(n/5)), n>=0.
a(n) ~ 3*n^(3/2) * exp(Pi*sqrt(2*n/3)) / (20*sqrt(2)*Pi^5). - Vaclav Kotesovec, Aug 28 2015

A085756 Number of partitions into a prime number of distinct parts.

Original entry on oeis.org

1, 1, 2, 3, 4, 5, 7, 8, 10, 12, 14, 16, 20, 22, 26, 30, 35, 40, 47, 53, 62, 71, 82, 93, 108, 123, 141, 161, 184, 209, 239, 271, 309, 350, 397, 449, 509, 575, 649, 732, 825, 928, 1044, 1172, 1315, 1474, 1650, 1845, 2061, 2300, 2563, 2854, 3174, 3526, 3912, 4337
Offset: 3

Views

Author

Vladeta Jovovic, Jul 21 2003

Keywords

Examples

			a(15)=20 because there are 20 partitions of 15 into a prime number of distinct parts: 1+2+3+4+5=4+5+6=3+5+7=2+6+7=3+4+8=2+5+8=1+6+8=7+8=2+4+9=1+5+9=6+9=2+3+10=
1+4+10=5+10=1+3+11=4+11=1+2+12=3+12=2+13=1+14.
		

Crossrefs

Cf. A038499.

Formula

a(n) = A004526(n-1) +A001399(n-6) +A001401(n-15) +A008636(n-28) + .... - R. J. Mathar, Feb 13 2019

A341912 Number of partitions of n into 5 distinct and relatively prime parts.

Original entry on oeis.org

1, 1, 2, 3, 5, 7, 10, 13, 18, 23, 30, 37, 47, 57, 70, 83, 101, 118, 141, 162, 192, 218, 255, 286, 333, 370, 427, 470, 540, 590, 673, 730, 831, 894, 1014, 1085, 1224, 1305, 1469, 1552, 1747, 1841, 2057, 2163, 2418, 2520, 2818, 2933, 3256, 3388, 3765, 3879, 4319, 4452, 4914, 5068
Offset: 15

Views

Author

Ilya Gutkovskiy, Feb 23 2021

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 70; CoefficientList[Series[Sum[MoebiusMu[k] x^(15 k)/Product[1 - x^(j k), {j, 1, 5}], {k, 1, nmax}], {x, 0, nmax}], x] // Drop[#, 15] &

Formula

G.f.: Sum_{k>=1} mu(k)* x^(15*k) / Product_{j=1..5} (1 - x^(j*k)).
a(n) <= A001401(n-15). - R. J. Mathar, Feb 28 2021

A117487 G.f.: 1/((1-x)*(1-x^2)*(1-x^3)*(1-x^4)*(1-x^5))^2.

Original entry on oeis.org

1, 2, 5, 10, 20, 36, 63, 104, 169, 264, 405, 604, 888, 1278, 1815, 2536, 3502, 4772, 6437, 8586, 11352, 14866, 19315, 24890, 31851, 40466, 51089, 64092, 79952, 99172, 122386, 150264, 183639, 223394, 270605, 326422, 392225, 469490, 559970, 665542, 788412
Offset: 1

Views

Author

Alford Arnold, Mar 22 2006

Keywords

Comments

Molien series for S_5 X S_5, cf. A001401.
Molien series for S_k X S_k approaches A000712 as k increases.
Column 5 of table A115994.
Note that a(5) is 20, the scalar product of (1 1 2 3 5) and (5 3 2 1 1 ). a(6) is 36, the scalar product of (1 1 2 3 5 7) and (7 5 3 2 1 1 ).

Crossrefs

Programs

  • Magma
    n:=5; G:=SymmetricGroup(n); H:=DirectProduct(G,G); MolienSeries(H); // N. J. A. Sloane
    
  • Maple
    # adapted from A115994 kmax := 120 : qmax := kmax/2 : g:=sum(t^k*q^(k^2)/product((1-q^j)^2, j=1..k), k=1..kmax): gser:=series(g, q=0, qmax): for n from 25 to qmax-1 do P :=coeff(gser, q^n) : printf("%a,",coeff(P, t^5)); od: # R. J. Mathar, Apr 07 2006
  • Mathematica
    CoefficientList[Series[1/(Product[(1-x^j), {j,5}])^2, {x,0,45}], x] (* G. C. Greubel, Jan 01 2020 *)
  • PARI
    my(x='x+O('x^45)); Vec( 1/(prod(j=1,5, 1-x^j))^2 ) \\ G. C. Greubel, Jan 01 2020
    
  • Sage
    def A117487_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/(product(1-x^j for j in (1..5)))^2 ).list()
    A117487_list(45) # G. C. Greubel, Jan 01 2020

Extensions

More terms from R. J. Mathar, Apr 07 2006
Entry revised by N. J. A. Sloane, Mar 10 2007

A145574 Array a(n,m) for number of partitions of n>=2 with m parts having no part 1. Hence m=1..floor(n/2).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 3, 2, 1, 1, 3, 3, 1, 1, 4, 4, 2, 1, 1, 4, 5, 3, 1, 1, 5, 7, 5, 2, 1, 1, 5, 8, 6, 3, 1, 1, 6, 10, 9, 5, 2, 1, 1, 6, 12, 11, 7, 3, 1, 1, 7, 14, 15, 10, 5, 2, 1, 1, 7, 16, 18, 13, 7, 3, 1, 1, 8, 19, 23, 18, 11, 5, 2, 1, 1, 8, 21, 27, 23, 14, 7, 3, 1, 1, 9, 24, 34, 30
Offset: 2

Views

Author

Wolfdieter Lang and Malin Sjodahl, Mar 06 2009

Keywords

Comments

The row lengths sequence is floor(n/2) = [1,1,2,2,3,3,4,4,...], see A008619(n-1), n>=2.
Obtained from the characteristic partition array A145573 by summing in row n>=2 over entries belonging to like parts number m.
The column sequences give A000012, A004526, A001399, A001400, A001401, A001402, A026813 for m=1..7.

Examples

			1;
1;
1, 1;
1, 1;
1, 2, 1;
1, 2, 1;
1, 3, 2, 1;
1, 3, 3, 1;
1, 4, 4, 2, 1;
		

Crossrefs

Cf. A145573, A002865 (row sums).

Programs

  • Maple
    b:= proc(n, i, t) option remember; `if`(2*t>n or t*i b(n, n, m):
    seq(seq(a(n, m), m=1..iquo(n, 2)), n=2..30); # Alois P. Heinz, Oct 18 2012
  • Mathematica
    nn=15; f[list_]:=Select[list,#>0&]; p=Product[1/(1-y x^i), {i, 2, nn}]; Drop[Map[f, CoefficientList[Series[p, {x, 0, nn}], {x, y}]], 1]//Grid  (* Geoffrey Critzer, Sep 23 2012 *)
  • Sage
    # Prints the table; cf. A011973.
    for n in (2..20): [Partitions(n, length=m, min_part=2).cardinality() for m in (1..n//2)]  # Peter Luschny, Oct 18 2012

Formula

a(n,m) = sum over entries of A145573(n,k) array which belong to partitions with part number m, for m=1..floor(n/2)). Note that partitions with parts number m>floor(n/2) have always at least one part 1.
G.f.: Product_{i>=2} 1/(1- y*x^i). - Geoffrey Critzer, Sep 23 2012

A256225 Number of partitions of 5n into 5 parts.

Original entry on oeis.org

0, 1, 7, 30, 84, 192, 377, 674, 1115, 1747, 2611, 3765, 5260, 7166, 9542, 12470, 16019, 20282, 25337, 31289, 38225, 46262, 55496, 66055, 78045, 91606, 106852, 123935, 142979, 164147, 187572, 213429, 241860, 273052, 307156, 344370, 384855, 428821, 476437, 527925
Offset: 0

Views

Author

Colin Barker, Mar 19 2015

Keywords

Examples

			For n=2, the 7 partitions of 10 are [6,1,1,1,1], [5,2,1,1,1], [4,3,1,1,1], [4,2,2,1,1], [3,3,2,1,1], [3,2,2,2,1] and [2,2,2,2,2].
		

Crossrefs

Programs

  • Mathematica
    Length /@ (Length /@ IntegerPartitions[5 #, {5}] & /@ Range@ 39) (* Michael De Vlieger, Mar 20 2015 *)
  • PARI
    concat(0, Vec(-x* (x^8+5*x^7+16*x^6+25*x^5+31*x^4+25*x^3+16*x^2+5*x+1) / ((x-1)^5*(x+1)^2*(x^2+1)*(x^2+x+1)) + O(x^100)))
    
  • PARI
    concat(0, vector(40, n, k=0; forpart(p=5*n, k++, , [5,5]); k)) \\ Colin Barker, Mar 21 2015

Formula

G.f.: -x*(x^8+5*x^7+16*x^6+25*x^5+31*x^4+25*x^3+16*x^2+5*x+1) / ((x-1)^5*(x+1)^2*(x^2+1)*(x^2+x+1)).

A091492 Triangle, read by rows, generated recursively and related to partitions.

Original entry on oeis.org

1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 2, 0, 0, 0, 1, 1, 2, 1, 0, 0, 0, 1, 1, 3, 1, 0, 0, 0, 0, 1, 1, 3, 2, 0, 0, 0, 0, 0, 1, 1, 4, 3, 0, 0, 0, 0, 0, 0, 1, 1, 4, 4, 1, 0, 0, 0, 0, 0, 0, 1, 1, 5, 5, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 5, 7, 2, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 6, 8, 3, 2, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Paul D. Hanna, Jan 16 2004

Keywords

Comments

Excluding the leading zeros, the columns are related to partitions. The 3rd column lists A001399 (partitions of n into at most 3 parts). The 4th column lists A001400 (partitions of n into at most 4 parts). The 5th column lists A001401 (partitions of n into at most 5 parts). The 6th column is A091498. Row sums are A091493. The number of nonzero terms in each row is A091497.

Examples

			T(12,3) = 7 = (4)*1+(3)*1 = T(9,2)*T(2,1)+T(9,3)*T(3,0) = Sum T(9,j)*T(j,3-j) {j=2..3}.
Rows begin:
{1},
{1,1},
{1,1,0},
{1,1,1,0},
{1,1,1,0,0},
{1,1,2,0,0,0},
{1,1,2,1,0,0,0},
{1,1,3,1,0,0,0,0},
{1,1,3,2,0,0,0,0,0},
{1,1,4,3,0,0,0,0,0,0},
{1,1,4,4,1,0,0,0,0,0,0},
{1,1,5,5,1,1,0,0,0,0,0,0},
{1,1,5,7,2,1,0,0,0,0,0,0,0},
{1,1,6,8,3,2,0,0,0,0,0,0,0,0},
{1,1,6,10,5,3,0,0,0,0,0,...
{1,1,7,12,6,5,0,0,0,0,0,...
{1,1,7,14,9,7,1,0,0,0,0,...
{1,1,8,16,11,10,2,0,0,0,...
{1,1,8,19,15,13,3,2,0,0,...
{1,1,9,21,18,18,5,2,0,0,...
{1,1,9,24,23,23,8,4,0,0,...
{1,1,10,27,27,30,11,6,0,...
{1,1,10,30,34,37,17,10,0,...
		

Crossrefs

Programs

  • PARI
    T(n,k)=if(k>n || n<0 || k<0,0,if(k<=1 || (k==n && n<2),1, sum(j=(k+1)\2,min(n-k,k),T(n-k,j)*T(j,k-j)););)

Formula

T(n, k)=Sum T(n-k, j)*T(j, k-j) {j=[(k+1)/2]..min(k, n-k)}, with T(0, 0)=1, T(n, 0)=1, T(1, 1)=1.

A139672 Convolution of A008619 and A001400.

Original entry on oeis.org

1, 2, 5, 9, 17, 27, 44, 65, 97, 136, 191, 257, 346, 451, 587, 746, 946, 1177, 1461, 1786, 2178, 2623, 3151, 3746, 4443, 5223, 6126, 7131, 8283, 9558, 11007, 12603, 14403, 16377, 18588, 21003, 23692, 26618, 29858, 33372, 37244, 41430, 46022, 50972
Offset: 1

Views

Author

Alford Arnold, Apr 29 2008, May 01 2008

Keywords

Comments

This is row 21 of a table of values related to Molien series. It is the product of the sequence on row 3 (A008619) with the sequence on row 7 (A001400).
This table may be constructed by moving the rows of table A008284 to prime locations and generating the composite locations by multiplication in a manner similar to the calculation illustrated in the present sequence.
Rows 1 thru 20 and 22 thru 25 are as follows:

Programs

  • Maple
    a:= proc(n) local m, r; m:= iquo (n, 12, 'r'); r:= r+1; (19+ (145+ (260+ 15* (r+9)*r+ (405+ 90*r+ 216*m) *m) *m) *m) *m/5+ [0, 1, 2, 5, 9, 17, 27, 44, 65, 97, 136, 191][r]+ [0, 16, 37, 77, 128, 208, 307, 447, 616, 840, 1105, 1441][r]*m/2+ [0, 52, 119, 213, 328, 476, 651, 865, 1112, 1404, 1735, 2117][r]*m^2/2 end: seq (a(n), n=1..50); # Alois P. Heinz, Nov 10 2008
  • Mathematica
    CoefficientList[Series[x/((x^2+x+1)(x^2+1)(x+1)^3 (x-1)^6),{x,0,50}],x] (* or *) LinearRecurrence[{2,1,-3,0,-1,2,2,-1,0,-3,1,2,-1},{0,1,2,5,9,17,27,44,65,97,136,191,257},50] (* Harvey P. Dale, Feb 17 2016 *)

Formula

G.f.: x/((x^2+x+1)*(x^2+1)*(x+1)^3*(x-1)^6). - Alois P. Heinz, Nov 10 2008
a(n)= -A049347(n)/27 +(2*n+11)*(6*n^4+132*n^3+914*n^2+2068*n+1055)/69120 -(-1)^n*(51/512+n^2/256+11*n/256+A057077(n)/32 ). - R. J. Mathar, Nov 21 2008

Extensions

More terms from Alois P. Heinz, Nov 10 2008
Corrected A-number in definition. Added formula. - R. J. Mathar, Nov 21 2008

A288166 Expansion of x^5/((1-x^5)*(1-x^4)*(1-x^8)*(1-x^12)*(1-x^16)).

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 2, 1, 1, 0, 3, 2, 1, 1, 5, 3, 2, 1, 7, 5, 3, 2, 10, 7, 5, 3, 13, 10, 7, 5, 18, 13, 10, 7, 23, 18, 13, 10, 30, 23, 18, 13, 37, 30, 23, 18, 47, 37, 30, 23, 57, 47, 37, 30, 70, 57, 47, 37, 84, 70, 57, 47, 101, 84, 70, 57, 119
Offset: 0

Views

Author

Seiichi Manyama, Jun 06 2017

Keywords

Examples

			a(56) = p_5(56/4)      = p_5(14) = A001401(9)  = 23,
a(57) = p_5((57+15)/4) = p_5(18) = A001401(13) = 57,
a(58) = p_5((58+10)/4) = p_5(17) = A001401(12) = 47,
a(59) = p_5((59+5)/4)  = p_5(16) = A001401(11) = 37,
a(60) = p_5(60/4)      = p_5(15) = A001401(10) = 30,
a(61) = p_5((61+15)/4) = p_5(19) = A001401(14) = 70,
a(62) = p_5((62+10)/4) = p_5(18) = A001401(13) = 57,
a(63) = p_5((63+5)/4)  = p_5(17) = A001401(12) = 47.
		

Crossrefs

Cf. A001401.
Cf. A005044 (k=3), A288165 (k=4), this sequence (k=5).

Programs

  • Mathematica
    CoefficientList[Series[x^5/((1-x^4)(1-x^5)(1-x^8)(1-x^12)(1-x^16)),{x,0,120}],x] (* or *) LinearRecurrence[ {0,0,0,1,1,0,0,1,-1,0,0,0,-1,0,0,0,0,0,0,-2,0,0,0,0,2,0,0,0,0,0,0,1,0,0,0,1,-1,0,0,-1,-1,0,0,0,1},{0,0,0,0,0,1,0,0,0,1,1,0,0,2,1,1,0,3,2,1,1,5,3,2,1,7,5,3,2,10,7,5,3,13,10,7,5,18,13,10,7,23,18,13,10},120] (* Harvey P. Dale, Apr 22 2019 *)

Formula

a(n) = p_5(n/4) if n == 0 mod 4,
a(n) = p_5((n+15)/4) if n == 1 mod 4,
a(n) = p_5((n+10)/4) if n == 2 mod 4,
a(n) = p_5((n+5)/4) if n == 3 mod 4,
where p_5(n) is the number of partitions of n into exactly 5 parts.
Previous Showing 11-20 of 27 results. Next