A205575 - OEIS

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A205575

Triangle read by rows, related to Pascal's triangle.

1, 1, 0, 2, 2, 1, 3, 5, 4, 1, 5, 12, 14, 8, 2, 8, 25, 38, 32, 15, 3, 13, 50, 94, 104, 71, 28, 5, 21, 96, 215, 293, 260, 149, 51, 8, 34, 180, 468, 756, 822, 612, 304, 92, 13, 55, 331, 980, 1828, 2346, 2136, 1376, 604, 164, 21

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

0,4

COMMENTS

Antidiagonal sums are in A052980, row sums are in A046717.

Similar to A091533 and to A091562. Triangle satisfying the same recurrence as A091533 and A091562, but with the initial values T(0,0) = 1, T(0,1) = 1, T(1,1) = 0.

LINKS

Table of n, a(n) for n=0..54.

FORMULA

T(n,k) = T(n-1,k) + T(n-1,k-1) + T(n-2,k) + T(n-2,k-1) + T(n-2,k-2) for n>=2, k>=0, with initial conditions specified by first two rows. T(0,0) = 1, T(1,0) = 1, T(1,1) = 0.

EXAMPLE

Triangle begins :

1, 0

2, 2, 1

3, 5, 4, 1

5, 12, 14, 8, 2

8, 25, 38, 32, 15, 3

13, 50, 94, 104, 71, 28, 5

PROG

(PARI) T(n, k) = {if(n<0, return(0)); if (n==0, if (k<0, return(0)); if (k==0, return(1))); if (n==1, if (k<0, return(0)); if (k==0, return(1)); if (k==1, return(0))); T(n-1, k)+T(n-1, k-1)+T(n-2, k)+T(n-2, k-1)+T(n-2, k-2); } \\ Michel Marcus, Oct 27 2021

CROSSREFS

Cf. Column 0: A000045, Diagonals : A000045, A029907, A036681.

Cf. A090171, A090172, A090173, A090174, A091533, A091562 (same recurrence).

Sequence in context: A099514 A228352 A303911 * A368338 A344583 A349414

Adjacent sequences: A205572 A205573 A205574 * A205576 A205577 A205578

KEYWORD

nonn,tabl

AUTHOR

Philippe Deléham, Jan 29 2012

EXTENSIONS

a(46), a(48) corrected by Georg Fischer, Oct 27 2021

STATUS

approved