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.

A294250 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f.: exp(Product_{j=1..n} (1+x^j) - 1).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 3, 1, 0, 1, 1, 3, 13, 1, 0, 1, 1, 3, 19, 49, 1, 0, 1, 1, 3, 19, 97, 261, 1, 0, 1, 1, 3, 19, 121, 681, 1531, 1, 0, 1, 1, 3, 19, 121, 921, 5971, 9073, 1, 0, 1, 1, 3, 19, 121, 1041, 8491, 50443, 63393, 1, 0, 1, 1, 3, 19, 121, 1041
Offset: 0

Views

Author

Seiichi Manyama, Oct 26 2017

Keywords

Examples

			Square array A(n,k) begins:
   1, 1,   1,   1,   1, ...
   0, 1,   1,   1,   1, ...
   0, 1,   3,   3,   3, ...
   0, 1,  13,  19,  19, ...
   0, 1,  49,  97, 121, ...
   0, 1, 261, 681, 921, ...
		

Crossrefs

Columns k=0..5 give A000007, A000012, A118589, A294251, A294252, A294253.
Rows n=0 gives A000012.
Main diagonal gives A293840.

Formula

B(j,k) is the coefficient of Product_{i=1..k} (1+x^i).
A(0,k) = 1 and A(n,k) = (n-1)! * Sum_{j=1..min(A000217(k),n)} j*B(j,k)*A(n-j,k)/(n-j)! for n > 0.

A293839 E.g.f.: exp(Sum_{n>=1} A000009(n)*x^n/n).

Original entry on oeis.org

1, 1, 2, 8, 38, 238, 1828, 16096, 160604, 1826684, 23018264, 316422304, 4755059848, 77084268712, 1343682876272, 25097562397952, 498130253334032, 10479084018025744, 233353674153699616, 5470193826634531456, 134766983204541259616, 3482705318091355591136
Offset: 0

Views

Author

Seiichi Manyama, Oct 17 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[E^Sum[PartitionsQ[k]*x^k/k, {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Oct 18 2017 *)

Formula

a(0) = 1 and a(n) = (n-1)! * Sum_{k=1..n} A000009(k)*a(n-k)/(n-k)! for n > 0.

A293528 E.g.f.: exp(x * Product_{k>0} (1 + x^k)).

Original entry on oeis.org

1, 1, 3, 13, 97, 741, 7291, 81313, 1027713, 14231017, 220911571, 3730744821, 68096325793, 1339705629133, 28225576881867, 634123159354441, 15127595174135041, 381586517104288593, 10147599723510322723, 283846981316172613597, 8324822922497497733601
Offset: 0

Views

Author

Seiichi Manyama, Oct 11 2017

Keywords

Comments

From Peter Bala, Mar 28 2022: (Start)
The congruence a(n+k) == a(n) (mod k) holds for all n and k.
It follows that the sequence obtained by taking a(n) modulo a fixed positive integer k is periodic with exact period dividing k. For example, the sequence taken modulo 10 becomes [1, 1, 3, 3, 7, 1, 1, 3, 3, 7, ...], a purely periodic sequence with period 5.
3 divides a(3*n+2); 13 divides a(13*n+3) and a(13*n+5); 19 divides a(19*n+5), a(19*n+12) and a(19*n+14). (End)

Crossrefs

Programs

  • Mathematica
    nmax = 25; CoefficientList[Series[E^(x*QPochhammer[-1, x]/2), {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Oct 11 2017 *)
  • PARI
    N=66; x='x+O('x^N); Vec(serlaplace(exp(x*prod(k=1, N, (1+x^k)))))

Formula

a(0) = 1 and a(n) = (n-1)! * Sum_{k=1..n} k*A000009(k-1)*a(n-k)/(n-k)! for n > 0.

A293841 E.g.f.: exp(Sum_{n>=1} n*A000009(n)*x^n).

Original entry on oeis.org

1, 1, 5, 49, 409, 4841, 66541, 1006825, 17349809, 333948529, 6997459861, 159199648961, 3918175462345, 103227624161689, 2901807752857469, 86684932131301561, 2738566218754961761, 91236821580866560865, 3196113263245038385189
Offset: 0

Views

Author

Seiichi Manyama, Oct 17 2017

Keywords

Comments

From Peter Bala, Mar 28 2022: (Start)
The congruence a(n+k) == a(n) (mod k) holds for all n and k.
It follows that the sequence obtained by taking a(n) modulo a fixed positive integer k is periodic with exact period dividing k. For example, the sequence taken modulo 10 becomes [1, 1, 5, 9, 9, 1, 1, 5, 9, 9, ...], a purely periodic sequence with exact period 5.
5 divides a(5*n+2), 7 divides a(7*n+3); 17 divides a(17*n+7), a(17*n+8) and a(17*n+11). (End)

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[E^Sum[k*PartitionsQ[k]*x^k, {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Oct 18 2017 *)

Formula

a(0) = 1 and a(n) = (n-1)! * Sum_{k=1..n} k^2*A000009(k)*a(n-k)/(n-k)! for n > 0.

A294260 E.g.f.: exp(Sum_{n>=1} A010815(n)*x^n).

Original entry on oeis.org

1, -1, -1, 5, 1, 79, -689, 2981, -7615, -172801, 3621151, -16469531, -240199871, 2722511375, 51840080111, -1987808959291, 12337235928961, 136594696115071, -1167414675803585, -56631124939839931, -1376838916423621759, 69766591820556094799
Offset: 0

Views

Author

Seiichi Manyama, Oct 26 2017

Keywords

Crossrefs

Main diagonal of A294254.
Cf. A293840.

Formula

a(0) = 1 and a(n) = (n-1)! * Sum_{k=1..n} k*A010815(k)*a(n-k)/(n-k)! for n > 0.

A294261 E.g.f.: exp(Sum_{n>=1} A081362(n)*x^n).

Original entry on oeis.org

1, -1, 1, -7, 49, -301, 2281, -21211, 260737, -3254329, 41086801, -589336111, 9851907121, -170708882917, 3060177746809, -60544788499651, 1298663388032641, -28777111728560881, 665551703689032097, -16413980708818538839, 428253175770218766001
Offset: 0

Views

Author

Seiichi Manyama, Oct 26 2017

Keywords

Crossrefs

Main diagonal of A294289.

Formula

a(0) = 1 and a(n) = (n-1)! * Sum_{k=1..n} k*A081362(k)*a(n-k)/(n-k)! for n > 0.

A300514 Expansion of e.g.f. exp(Sum_{k>=1} q(k)*x^k/k!), where q(k) = number of partitions of k into distinct parts (A000009).

Original entry on oeis.org

1, 1, 2, 6, 20, 79, 358, 1791, 9854, 58958, 379716, 2617320, 19197327, 149099827, 1221390172, 10515829901, 94865603724, 894302028718, 8788782784778, 89848652800152, 953666248076772, 10491219933196228, 119429574273909421, 1404835599743325765, 17052591331677804136
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 07 2018

Keywords

Comments

Exponential transform of A000009.

Examples

			E.g.f.: A(x) = 1 + x/1! + 2*x^2/2! + 6*x^3/3! + 20*x^4/4! + 79*x^5/5! + 358*x^6/6! + 1791*x^7/7! + ...
		

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1, add(b(n-j)*add(
         `if`(d::odd, d, 0), d=numtheory[divisors](j)), j=1..n)/n)
        end:
    a:= proc(n) option remember; `if`(n=0, 1, add(
          a(n-j)*binomial(n-1, j-1)*b(j), j=1..n))
        end:
    seq(a(n), n=0..30);  # Alois P. Heinz, Mar 07 2018
  • Mathematica
    nmax = 24; CoefficientList[Series[Exp[Sum[PartitionsQ[k] x^k/k!, {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
    a[n_] := a[n] = Sum[PartitionsQ[k] Binomial[n - 1, k - 1] a[n - k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 24}]

Formula

E.g.f.: exp(Sum_{k>=1} A000009(k)*x^k/k!).

A327674 Number of colored compositions of n using all colors of an n-set such that the color patterns for parts i are sorted and have i (distinct) colors (in arbitrary order).

Original entry on oeis.org

1, 1, 3, 19, 121, 1041, 11191, 130663, 1731969, 25778161, 432791371, 7752723771, 151553121193, 3178030999729, 71244609480591, 1716351868658911, 43661944977384961, 1173984102030774753, 33302371396771085779, 991402105480284394531, 30912472614894951462681
Offset: 0

Views

Author

Alois P. Heinz, Sep 21 2019

Keywords

Comments

Differs from A293840 and from A294253 first at n = 6.

Examples

			a(3) = 19: 3abc, 3acb, 3bac, 3bca, 3cab, 3cba, 2ab1c, 2ac1b, 2ba1c, 2bc1a, 2ca1b, 2cb1a, 1a2bc, 1a2cb, 1b2ac, 1b2ca, 1c2ab, 1c2ba, 1a1b1c.
		

Crossrefs

Main diagonal of A327673.

Programs

  • Maple
    b:= proc(n, i, k, p) option remember;
         `if`(n=0, p!, `if`(i<1, 0, add(binomial(k^i, j)*
          b(n-i*j, min(n-i*j, i-1), k, p+j)/j!, j=0..n/i)))
        end:
    a:= n-> add(b(n$2, i, 0)*(-1)^(n-i)*binomial(n, i), i=0..n):
    seq(a(n), n=0..21);
  • Mathematica
    b[n_, i_, k_, p_] := b[n, i, k, p] =
         If[n == 0, p!, If[i < 1, 0, Sum[Binomial[k^i, j]*
         b[n - i j, Min[n - i j, i - 1], k, p + j]/j!, {j, 0, n/i}]]];
    a[n_] := Sum[b[n, n, i, 0] (-1)^(n-i) Binomial[n, i], {i, 0, n}];
    Table[a[n], {n, 0, 21}] (* Jean-François Alcover, Aug 01 2021, after Alois P. Heinz *)

Formula

a(n) = A327673(n,n).

A293908 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f.: exp(Sum_{j>=1} j^(k-1)*A000009(j)*x^j).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 3, 8, 1, 1, 5, 19, 38, 1, 1, 9, 49, 121, 238, 1, 1, 17, 133, 409, 1041, 1828, 1, 1, 33, 373, 1441, 4841, 10651, 16096, 1, 1, 65, 1069, 5233, 23601, 66541, 121843, 160604, 1, 1, 129, 3109, 19441, 119441, 442681, 1006825, 1575729, 1826684, 1, 1
Offset: 0

Views

Author

Seiichi Manyama, Oct 19 2017

Keywords

Examples

			Square array begins:
     1,    1,    1,     1,      1, ...
     1,    1,    1,     1,      1, ...
     2,    3,    5,     9,     17, ...
     8,   19,   49,   133,    373, ...
    38,  121,  409,  1411,   5233, ...
   238, 1041, 4841, 23601, 119441, ...
		

Crossrefs

Columns k=0..2 give A293839, A293840, A293841.
Rows n=0-1 give A000012.
Cf. A293796.

Formula

A(0,k) = 1 and A(n,k) = (n-1)! * Sum_{j=1..n} j^k*A000009(j)*A(n-j,k)/(n-j)! for n > 0.

A320899 Expansion of e.g.f. exp(1/theta_4(x) - 1), where theta_4() is the Jacobi theta function.

Original entry on oeis.org

1, 2, 12, 104, 1120, 14592, 221824, 3835904, 74262528, 1589016320, 37181031424, 943547716608, 25791165349888, 754934109863936, 23547020011929600, 779291847538638848, 27263652732032843776, 1005002283128197349376, 38921431600215853760512, 1579513585265275661189120
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 23 2018

Keywords

Crossrefs

Programs

  • Maple
    seq(coeff(series(factorial(n)*(exp(-1+mul((1+x^k)/(1-x^k),k=1..n))),x,n+1), x, n), n = 0 .. 20); # Muniru A Asiru, Oct 23 2018
  • Mathematica
    nmax = 19; CoefficientList[Series[Exp[1/EllipticTheta[4, 0, x] - 1], {x, 0, nmax}], x] Range[0, nmax]!
    a[n_] := a[n] = Sum[Sum[PartitionsP[k - j] PartitionsQ[j], {j, 0, k}] k! Binomial[n - 1, k - 1] a[n - k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 19}]

Formula

E.g.f.: exp(-1 + Product_{k>=1} (1 + x^k)/(1 - x^k)).
a(0) = 1; a(n) = Sum_{k=1..n} A015128(k)*k!*binomial(n-1,k-1)*a(n-k).
Showing 1-10 of 10 results.