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.

A102473 Triangle read by rows. Let S(k) be the sequence defined by F(0)=0, F(1)=1, F(n-1) + (n+k)*F(n) = F(n+1). E.g. S(0) = 0,1,1,3,10,43,225,1393,9976,81201, ... Then S(0), S(1), S(2), ... are written next to each other, vertically, with the initial term of each on the next row down. The order of the terms in the rows are then reversed.

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 1, 3, 7, 10, 1, 4, 13, 30, 43, 1, 5, 21, 68, 157, 225, 1, 6, 31, 130, 421, 972, 1393, 1, 7, 43, 222, 931, 3015, 6961, 9976, 1, 8, 57, 350, 1807, 7578, 24541, 56660, 81201, 1, 9, 73, 520, 3193, 16485, 69133, 223884, 516901, 740785, 1, 10, 91, 738
Offset: 1

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Author

Russell Walsmith (russw(AT)lycos.com), Jan 09 2005

Keywords

Comments

For this triangle, the algorithm that generates the Bernoulli numbers gives 3/2, then 1/6, 1/24, ... 1/n!
T(n,n) = A001040(n); T(n,k) = A058294(n,k), k = 1..n. - Reinhard Zumkeller, Sep 14 2014

Examples

			Triangle begins:
0
0 1
0 1 1
0 1 2 3
0 1 3 7 10
0 1 4 13 30 43
...
(the zeros are omitted).
		

Crossrefs

Mirror image of triangle in A102472.
Cf. A001040, A058294, A247365 (central terms).

Programs

  • Haskell
    a102473 n k = a102473_tabl !! (n-1) !! (k-1)
    a102473_row n = a102473_tabl !! (n-1)
    a102473_tabl = [1] : [1, 1] : f [1] [1, 1] 2 where
       f us vs x = ws : f vs ws (x + 1) where
                   ws = 1 : zipWith (+) ([0] ++ us) (map (* x) vs)
    -- Reinhard Zumkeller, Sep 14 2014

Extensions

Entry revised by N. J. A. Sloane, Jul 09 2005