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 1-6 of 6 results.

A144254 Eigentriangle by rows, termwise products of A078812 and its eigensequence, A125274.

Original entry on oeis.org

1, 2, 1, 3, 4, 3, 4, 10, 18, 10, 5, 20, 63, 80, 42, 6, 35, 168, 360, 420, 210, 7, 56, 378, 1200, 2310, 2520, 1199, 8, 84, 756, 3300, 9240, 16380, 16786, 7670, 9, 120, 1386, 7920, 30030, 76440, 125895, 122720, 54224, 10, 165, 2376, 17160, 84084, 286650
Offset: 1

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Author

Gary W. Adamson, Sep 16 2008

Keywords

Comments

Right border A144253 = A125274, the eigensequence of A078812: (1, 1, 3, 10, 42, 210, 1199,...).
Row sums = A125274 shifted.
Sum of row n terms = rightmost term of next row.

Examples

			First few rows of the triangle =
1;
2, 1;
3, 4, 3;
4, 10, 18, 10;
5, 20, 63, 80, 42;
6, 35, 168, 360, 420, 210;
7, 56, 378, 1200, 2310, 2520, 1199;
...
Triangle A078812 begins:
1;
2, 1;
3, 4, 1;
4, 10, 6, 1;
5, 20, 21, 8, 1;
...
Its eigensequence = A125274: (1, 1, 3, 10, 42, 210, 1199,...).
Row 3 of triangle A144253 = termwise products of (4, 10, 6, 1) and (1, 1, 3, 10) = (4*1, 10*1, 6*3, 1*10).
		

Crossrefs

Formula

Eigensequence by rows, T(n,k) = A078812(n,k) * A125274(k).

A125273 Eigensequence of triangle A085478: a(n) = Sum_{k=0..n-1} A085478(n-1,k)*a(k) for n > 0 with a(0) = 1.

Original entry on oeis.org

1, 1, 2, 6, 23, 106, 567, 3434, 23137, 171174, 1376525, 11934581, 110817423, 1095896195, 11487974708, 127137087319, 1480232557526, 18075052037054, 230855220112093, 3076513227516437, 42686898298650967, 615457369662333260
Offset: 0

Views

Author

Paul D. Hanna, Nov 26 2006

Keywords

Examples

			a(3) = 1*(1) + 3*(1) + 1*(2) = 6;
a(4) = 1*(1) + 6*(1) + 5*(2) + 1*(6) = 23;
a(5) = 1*(1) + 10*(1) + 15*(2) + 7*(6) + 1*(23) = 106.
Triangle A085478(n,k) = binomial(n+k, n-k) (with rows n >= 0 and columns k = 0..n) begins:
  1;
  1,  1;
  1,  3,  1;
  1,  6,  5,  1;
  1, 10, 15,  7,  1;
  1, 15, 35, 28,  9,  1;
  ...
where g.f. of column k = 1/(1-x)^(2*k+1).
		

Crossrefs

Cf. A085478, A125274 (variant), A351813.

Programs

  • Mathematica
    A125273=ConstantArray[0,20]; A125273[[1]]=1; Do[A125273[[n]]=1+Sum[A125273[[k]]*Binomial[n+k-1, n-k-1],{k,1,n-1}];,{n,2,20}]; Flatten[{1,A125273}] (* Vaclav Kotesovec, Dec 10 2013 *)
  • PARI
    a(n)=if(n==0,1,sum(k=0,n-1, a(k)*binomial(n+k-1, n-k-1)))

Formula

a(n) = Sum_{k=0..n-1} binomial(n+k-1, n-k-1)*a(k) for n > 0 with a(0) = 1.
G.f. satisfies: A(x) = 1 + x*A(x/(1-x)^2) / (1-x). - Paul D. Hanna, Aug 15 2007

A351816 G.f. A(x) satisfies: A(x) = 1 + x * A(x/(1 - x)^3) / (1 - x)^3.

Original entry on oeis.org

1, 1, 4, 16, 83, 526, 3826, 31338, 285556, 2857831, 31083421, 364523891, 4579906098, 61313286380, 870531542926, 13055593578453, 206097824225131, 3414146518958089, 59189048364709453, 1071264611091540458, 20197719805598878119, 395917304689782855768
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 20 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 21; A[] = 0; Do[A[x] = 1 + x A[x/(1 - x)^3]/(1 - x)^3 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n + 2 k + 1, n - k - 1] a[k], {k, 0, n - 1}]; Table[a[n], {n, 0, 21}]

Formula

a(0) = 1; a(n) = Sum_{k=0..n-1} binomial(n+2*k+1,n-k-1) * a(k).

A351817 G.f. A(x) satisfies: A(x) = 1 + x * A(x/(1 - x)^4) / (1 - x)^4.

Original entry on oeis.org

1, 1, 5, 23, 139, 1052, 9166, 90073, 989205, 11981051, 158149438, 2255926638, 34549223880, 564898101239, 9812669832553, 180324597042263, 3492960489714519, 71092066388237562, 1516044005669227542, 33788707128788508476, 785270646437483414261, 18992014442689191510460
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 20 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 21; A[] = 0; Do[A[x] = 1 + x A[x/(1 - x)^4]/(1 - x)^4 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n + 3 k + 2, n - k - 1] a[k], {k, 0, n - 1}]; Table[a[n], {n, 0, 21}]

Formula

a(0) = 1; a(n) = Sum_{k=0..n-1} binomial(n+3*k+2,n-k-1) * a(k).

A351818 G.f. A(x) satisfies: A(x) = 1 + x * A(x/(1 - x)^5) / (1 - x)^5.

Original entry on oeis.org

1, 1, 6, 31, 211, 1841, 18547, 210664, 2682657, 37807531, 581985596, 9696297528, 173702897000, 3327063115248, 67790086866271, 1462900566163696, 33310115601839624, 797687851718024035, 20032231443590167914, 526189230537615409571, 14423255501358439152231
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 20 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; A[] = 0; Do[A[x] = 1 + x A[x/(1 - x)^5]/(1 - x)^5 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n + 4 k + 3, n - k - 1] a[k], {k, 0, n - 1}]; Table[a[n], {n, 0, 20}]

Formula

a(0) = 1; a(n) = Sum_{k=0..n-1} binomial(n+4*k+3,n-k-1) * a(k).

A351659 G.f. A(x) satisfies: A(x) = 1 - x * A(x/(1 - x)^2) / (1 - x)^2.

Original entry on oeis.org

1, -1, -1, 2, 10, 10, -97, -638, -1316, 9908, 118713, 560533, -697429, -38229322, -364288567, -1441996161, 11586777849, 281338444108, 2772828770441, 10249821640498, -170439385810217, -4104012197171264, -46232949019802137, -204897893603728741, 3708422726478663919
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 16 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 24; A[] = 0; Do[A[x] = 1 - x A[x/(1 - x)^2]/(1 - x)^2 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[0] = 1; a[n_] := a[n] = -Sum[Binomial[n + k, n - k - 1] a[k], {k, 0, n - 1}]; Table[a[n], {n, 0, 24}]

Formula

a(0) = 1; a(n) = -Sum_{k=0..n-1} binomial(n+k,n-k-1) * a(k).
Showing 1-6 of 6 results.