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.

Showing 1-10 of 10 results.

A341243 Expansion of (-1 + Product_{k>=1} 1 / (1 + (-x)^k))^4.

Original entry on oeis.org

1, 0, 4, 4, 10, 16, 26, 44, 63, 100, 144, 212, 297, 420, 584, 796, 1081, 1452, 1940, 2556, 3355, 4372, 5668, 7288, 9327, 11892, 15076, 19012, 23884, 29904, 37276, 46284, 57276, 70680, 86918, 106528, 130220, 158784, 193054, 234076, 283178, 341824, 411616, 494512, 592933
Offset: 4

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([0, d, -d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, g(n)),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 4):
    seq(a(n), n=4..48);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 48; CoefficientList[Series[(-1 + Product[1/(1 + (-x)^k), {k, 1, nmax}])^4, {x, 0, nmax}], x] // Drop[#, 4] &

Formula

G.f.: (-1 + Product_{k>=1} (1 + x^(2*k - 1)))^4.
a(n) ~ A112160(n). - Vaclav Kotesovec, Feb 20 2021

A060642 Triangle read by rows: row n lists number of ordered partitions into k parts of partitions of n.

Original entry on oeis.org

1, 2, 1, 3, 4, 1, 5, 10, 6, 1, 7, 22, 21, 8, 1, 11, 43, 59, 36, 10, 1, 15, 80, 144, 124, 55, 12, 1, 22, 141, 321, 362, 225, 78, 14, 1, 30, 240, 669, 944, 765, 370, 105, 16, 1, 42, 397, 1323, 2266, 2287, 1437, 567, 136, 18, 1, 56, 640, 2511, 5100, 6215, 4848, 2478, 824, 171, 20, 1
Offset: 1

Views

Author

Alford Arnold, Apr 16 2001

Keywords

Comments

Also the convolution triangle of A000041. - Peter Luschny, Oct 07 2022

Examples

			Table begins:
   1;
   2,   1;
   3,   4,    1;
   5,  10,    6,    1;
   7,  22,   21,    8,    1;
  11,  43,   59,   36,   10,    1;
  15,  80,  144,  124,   55,   12,   1;
  22, 141,  321,  362,  225,   78,  14,   1;
  30, 240,  669,  944,  765,  370, 105,  16,  1;
  42, 397, 1323, 2266, 2287, 1437, 567, 136, 18, 1;
  ...
For n=4 there are 5 partitions of 4, namely 4, 31, 22, 211, 11111. There are 5 ways to pick 1 of them; 10 ways to partition one of them into 2 ordered parts: 3,1; 1,3; 2,2; 21,1; 1,21; 2,11; 11,2; 111,1; 1,111; 11,11; 6 ways to partition one of them into 3 ordered parts: 2,1,1; 1,2,1; 1,1,2; 11,1,1; 1,11,1; 1,1,11; and one way to partition one of them into 4 ordered parts: 1,1,1,1. So row 4 is 5,10,6,1.
		

Crossrefs

Row sums give A055887.
T(2n,n) gives A340987.

Programs

  • Maple
    A:= proc(n, k) option remember; `if`(n=0, 1, k*add(
          A(n-j, k)*numtheory[sigma](j), j=1..n)/n)
        end:
    T:= (n, k)-> add(A(n, k-i)*(-1)^i*binomial(k, i), i=0..k):
    seq(seq(T(n, k), k=1..n), n=1..12);  # Alois P. Heinz, Mar 12 2015
    # Uses function PMatrix from A357368. Adds row and column for n, k = 0.
    PMatrix(10, combinat:-numbpart); # Peter Luschny, Oct 07 2022
  • Mathematica
    A[n_, k_] := A[n, k] = If[n==0, 1, k*Sum[A[n-j, k]*DivisorSigma[1, j], {j, 1, n}]/n]; T[n_, k_] := Sum[A[n, k-i]*(-1)^i*Binomial[k, i], {i, 0, k}]; Table[ Table[ T[n, k], {k, 1, n}], {n, 1, 12}] // Flatten (* Jean-François Alcover, Jul 15 2015, after Alois P. Heinz *)

Formula

G.f. A(n;x) for n-th row satisfies A(n;x) = Sum_{k=0..n-1} A000041(n-k)*A(k;x)*x, A(0;x) = 1. - Vladeta Jovovic, Jan 02 2004
T(n,k) = Sum_{i=0..k} (-1)^i * C(k,i) * A144064(n,k-i). - Alois P. Heinz, Mar 12 2015
Sum_{k=1..n} k * T(n,k) = A326346(n). - Alois P. Heinz, Sep 11 2019
Sum_{k=0..n} (-1)^k * T(n,k) = A010815(n). - Alois P. Heinz, Feb 07 2021
G.f. of column k: (-1 + Product_{j>=1} 1 / (1 - x^j))^k. - Ilya Gutkovskiy, Feb 13 2021

Extensions

More terms from Vladeta Jovovic, Jan 02 2004

A341221 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^3.

Original entry on oeis.org

1, 6, 21, 59, 144, 321, 669, 1323, 2511, 4604, 8202, 14253, 24241, 40449, 66363, 107234, 170910, 269004, 418566, 644436, 982536, 1484482, 2223942, 3305484, 4876620, 7144455, 10398123, 15039564, 21624678, 30919323, 43973708, 62222844, 87619212, 122810585
Offset: 3

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 3):
    seq(a(n), n=3..36);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 36; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^3, {x, 0, nmax}], x] // Drop[#, 3] &

Formula

a(n) ~ A000716(n). - Vaclav Kotesovec, Feb 20 2021

A341223 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^5.

Original entry on oeis.org

1, 10, 55, 225, 765, 2287, 6215, 15680, 37265, 84300, 182933, 383070, 777705, 1536490, 2963120, 5592060, 10349465, 18817760, 33665870, 59341785, 103176877, 177131330, 300530125, 504318530, 837632700, 1377874861, 2246061540, 3630059510, 5819556060, 9258393655, 14622472250
Offset: 5

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 5):
    seq(a(n), n=5..35);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 35; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^5, {x, 0, nmax}], x] // Drop[#, 5] &

A341225 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^6.

Original entry on oeis.org

1, 12, 78, 370, 1437, 4848, 14719, 41148, 107610, 266296, 628941, 1427118, 3127369, 6646440, 13746081, 27744926, 54782271, 106029918, 201512970, 376630680, 693161334, 1257641676, 2251764699, 3982196910, 6961522279, 12038699766, 20607718317, 34938910360
Offset: 6

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 6):
    seq(a(n), n=6..33);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 33; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^6, {x, 0, nmax}], x] // Drop[#, 6] &

A341226 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^7.

Original entry on oeis.org

1, 14, 105, 567, 2478, 9317, 31269, 95965, 273896, 735966, 1879059, 4591342, 10797290, 24549924, 54171729, 116368308, 243991034, 500446135, 1006039762, 1985480063, 3852429483, 7358212272, 13850448185, 25718189483, 47150564517, 85417834621, 153015826880
Offset: 7

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 7):
    seq(a(n), n=7..33);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 33; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^7, {x, 0, nmax}], x] // Drop[#, 7] &

A341227 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^8.

Original entry on oeis.org

1, 16, 136, 824, 4004, 16608, 61076, 204200, 631714, 1831752, 5027312, 13159104, 33049090, 80030808, 187613348, 427201176, 947520103, 2051989360, 4347996772, 9030416704, 18412343832, 36905322248, 72807201940, 141525042736, 271321432489, 513454659312
Offset: 8

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 8):
    seq(a(n), n=8..33);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 33; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^8, {x, 0, nmax}], x] // Drop[#, 8] &

A341228 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^9.

Original entry on oeis.org

1, 18, 171, 1149, 6147, 27891, 111567, 403722, 1345896, 4189334, 12300174, 34337403, 91721385, 235645425, 584759880, 1406588073, 3289489002, 7498465029, 16697615817, 36391839264, 77758115283, 163123713621, 336420277812, 682877289213, 1365674365197, 2693384989056
Offset: 9

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 9):
    seq(a(n), n=9..34);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 34; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^9, {x, 0, nmax}], x] // Drop[#, 9] &

A341365 Expansion of (1 / theta_4(x) - 1)^4 / 16.

Original entry on oeis.org

1, 8, 40, 156, 520, 1552, 4262, 10960, 26716, 62276, 139744, 303412, 640001, 1315832, 2644004, 5204044, 10052182, 19086348, 35672516, 65708116, 119409576, 214289116, 380068582, 666723748, 1157550524, 1990230968, 3390558072, 5726064688, 9590759624, 15938198484, 26289242026
Offset: 4

Views

Author

Ilya Gutkovskiy, Feb 10 2021

Keywords

Crossrefs

Programs

  • Maple
    g:= proc(n, i) option remember; `if`(n=0, 1/2, `if`(i=1, 0,
          g(n, i-1))+add(2*g(n-i*j, i-1), j=`if`(i=1, n, 1)..n/i))
        end:
    b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0,
          g(n$2)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    a:= n-> b(n, 4):
    seq(a(n), n=4..34);  # Alois P. Heinz, Feb 10 2021
  • Mathematica
    nmax = 34; CoefficientList[Series[(1/EllipticTheta[4, 0, x] - 1)^4/16, {x, 0, nmax}], x] // Drop[#, 4] &
    nmax = 34; CoefficientList[Series[(1/16) (-1 + Product[(1 + x^k)/(1 - x^k), {k, 1, nmax}])^4, {x, 0, nmax}], x] // Drop[#, 4] &

Formula

G.f.: (1/16) * (-1 + Product_{k>=1} (1 + x^k) / (1 - x^k))^4.
a(n) ~ A284286(n)/16. - Vaclav Kotesovec, Feb 20 2021

A341236 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^10.

Original entry on oeis.org

1, 20, 210, 1550, 9055, 44624, 192945, 751480, 2686155, 8934560, 27946335, 82884860, 234636435, 637416140, 1669127130, 4228739712, 10398140075, 24882425770, 58080468790, 132508486900, 296005537183, 648445364080, 1394961003490, 2950516502980, 6142674032345, 12599932782780
Offset: 10

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 10):
    seq(a(n), n=10..35);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 35; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^10, {x, 0, nmax}], x] // Drop[#, 10] &
Showing 1-10 of 10 results.