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A128226 Triangle, A004736 * A127899 (unsigned). 1
1, 4, 2, 7, 7, 3, 10, 12, 10, 4, 13, 17, 17, 13, 5, 16, 22, 24, 22, 16, 6, 19, 27, 31, 31, 27, 19, 7, 22, 32, 38, 40, 38, 32, 22, 8, 25, 37, 45, 49, 49, 45, 37, 25, 9, 28, 42, 52, 58, 60, 58, 52, 42, 28, 10 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row sums = A084990: (1, 6, 17, 36, 65, 106, ...).

A128225 = A127899(unsigned) * A004736.

LINKS

Table of n, a(n) for n=1..55.

FORMULA

A004736 * A127899 (unsigned). By columns, (3k+1), (5k+2), (7k+3),...; k=0,1,2...

EXAMPLE

First few row of the triangle are:

   1;

   4,  2;

   7,  7,  3;

  10, 12, 10,  4;

  13, 17, 17, 13,  5;

  16, 22, 24, 22, 16,  6;

  19, 27, 31, 31, 27, 19,  7;

  ...

MATHEMATICA

(* a127899U computes the unsigned version of A127899 *)

a127899U[n_, k_] := If[n==k||n-1==k, n, 0]/; (1<=k<=n)

a004736[n_, k_] := n-k+1/; (1<=k<=n+1)

a128225[n_, k_] := a127899U[n, n](a004736[n, k] + a004736[n-1, k])/; (1<=k<=n)

a128225[r_] := Table[a128225[n, k], {n, 1, r}, {k, 1, n}]

TableForm[a128225[7]] (* triangle *)

Flatten[a128225[10]] (* data *) (* Hartmut F. W. Hoft, Mar 13 2017 *)

CROSSREFS

Cf. A004736, A084990, A127899, A128225.

Sequence in context: A237750 A249652 A110841 * A049817 A203575 A120871

Adjacent sequences:  A128223 A128224 A128225 * A128227 A128228 A128229

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Feb 19 2007

STATUS

approved

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Last modified July 17 16:38 EDT 2019. Contains 325107 sequences. (Running on oeis4.)