A128226 - OEIS

A128226

Triangle, A004736 * A127899 (unsigned).

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

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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:

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: A249652 A110841 A380547 * A049817 A203575 A379565

Adjacent sequences: A128223 A128224 A128225 * A128227 A128228 A128229

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Feb 19 2007

STATUS

approved