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 1-5 of 5 results.

A144271 Row sums of triangle A144270 (called S2hat(-1)).

Original entry on oeis.org

1, 2, 5, 21, 129, 1099, 11647, 148292, 2190302, 36842892, 694276152, 14488348603, 331537914373, 8254117606799, 222087256536602, 6421589319659283, 198565371839434761, 6538245667687424041, 228396692050813678534, 8436237099236470594589
Offset: 1

Views

Author

Wolfdieter Lang, Oct 09 2008

Keywords

Crossrefs

Cf. A144270.

Formula

a(n) = Sum_{m=1..n} A144270(n,m), n>=1.

A144272 Second column (m=2) of triangle S2hat(-1) = A144270.

Original entry on oeis.org

1, 1, 4, 18, 129, 1095, 11880, 149940, 2218545, 37147005, 699281100, 14561835750, 332913128625, 8280095098275, 222659485448400, 6434896997529000, 198909798356894625, 6547761582390653625, 228681849947367316500, 8445341134525197152250, 328822530412023653630625
Offset: 0

Views

Author

Wolfdieter Lang, Oct 09 2008

Keywords

Crossrefs

Cf. A144270.
Cf. A001147 (column m=1), A144273 (column m=3).

Formula

a(n) = A144270(n+2,2), n>=0.

A144273 Third column (m=3) of triangle S2hat(-1) = A144270.

Original entry on oeis.org

1, 1, 4, 19, 132, 1119, 12057, 151560, 2234970, 37355130, 702161460, 14608747440, 333760916475, 8297318063475, 223043540630400, 6444290305953675, 199158606533605950, 6554872218153191625, 228899544451085017125, 8452452568601816775000, 329069272855540304587500
Offset: 0

Views

Author

Wolfdieter Lang, Oct 09 2008

Keywords

Crossrefs

Cf. A144270, A144272 (column m=2).

Formula

a(n) = A144270(n+3,3), n>=0.

A144275 Lower triangular array called S2hat(-2) related to partition number array A144274.

Original entry on oeis.org

1, 2, 1, 10, 2, 1, 80, 14, 2, 1, 880, 100, 14, 2, 1, 12320, 1140, 108, 14, 2, 1, 209440, 14880, 1180, 108, 14, 2, 1, 4188800, 249280, 15400, 1196, 108, 14, 2, 1, 96342400, 4801280, 255400, 15480, 1196, 108, 14, 2, 1, 2504902400, 108574400, 4888960, 256440, 15512
Offset: 1

Views

Author

Wolfdieter Lang, Oct 09 2008

Keywords

Comments

If in the partition array M32khat(-2)= A144274 entries with the same parts number m are summed one obtains this triangle of numbers S2hat(-2). In the same way the Stirling2 triangle A008277 is obtained from the partition array M_3 = A036040.
The first three columns are A008544, A144277, A144278.

Examples

			Triangle begins:
  [1];
  [2,1];
  [10,2,1];
  [80,14,2,1];
  [880,100,14,2,1];
  ...
		

Crossrefs

Row sums A144276.
A144270 (S2hat(-1)).

Formula

a(n,m) = Sum_{q=1..p(n,m)} (Product_{j=1..n} |S2(-2;j,1)|^e(n,m,q,j)) if n>=m>=1, else 0. Here p(n,m) = A008284(n,m), the number of m parts partitions of n and e(n,m,q,j) is the exponent of j in the q-th m part partition of n. |S2(-2,n,1)|= A004747(n,1) = A008544(n-1) = (3*n-4)(!^3) (3-factorials) for n>=2 and 1 if n=1.

A144269 Partition number array, called M32hat(-1)= 'M32(-1)/M3'= 'A143171/A036040', related to A001497(n-1,m-1)= |S2(-1;n,m)| (generalized Stirling triangle).

Original entry on oeis.org

1, 1, 1, 3, 1, 1, 15, 3, 1, 1, 1, 105, 15, 3, 3, 1, 1, 1, 945, 105, 15, 9, 15, 3, 1, 3, 1, 1, 1, 10395, 945, 105, 45, 105, 15, 9, 3, 15, 3, 1, 3, 1, 1, 1, 135135, 10395, 945, 315, 225, 945, 105, 45, 15, 9, 105, 15, 9, 3, 1, 15, 3, 1, 3, 1, 1, 1, 2027025, 135135, 10395, 2835
Offset: 1

Views

Author

Wolfdieter Lang, Oct 09 2008

Keywords

Comments

Each partition of n, ordered as in Abramowitz-Stegun (A-St order; for the reference see A134278), is mapped to a nonnegative integer a(n,k) =: M32hat(-1;n,k) with the k-th partition of n in A-St order.
The sequence of row lengths is A000041 (partition numbers) [1, 2, 3, 5, 7, 11, 15, 22, 30, 42,...].
If M32hat(-1;n,k) is summed over those k with fixed number of parts m one obtains triangle S2hat(-1):= A144270(n,m).

Examples

			a(4,3)= 1 = |S2(-1,2,1)|^2. The relevant partition of 4 is (2^2).
[1]; [1,1]; [3,1,1]; [15,3,1,1,1]; [105,15,3,3,1,1,1]; ... [From _Wolfdieter Lang_, Oct 23 2008]
		

Crossrefs

Cf. A144271 (M32hat(-2) array).

Formula

a(n,k)= product(|S2(-1,j,1)|^e(n,k,j),j=1..n) with |S2(-1,n,1)|= A001147(n-1) = (2*n-3)(!^2) (2-factorials) for n>=2 and 1 if n=1 and the exponent e(n,k,j) of j in the k-th partition of n in the A-St ordering of the partitions of n.
Formally a(n,k)= 'M32(-1)/M3' = 'A143171/A036040' (elementwise division of arrays).

Extensions

Corrected all entries. Wolfdieter Lang, Oct 23 2008
Showing 1-5 of 5 results.