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A128078 A002260 * A128064. 2

%I

%S 1,-1,4,-1,-2,9,-1,-2,-3,16,-1,-2,-3,-4,25,-1,-2,-3,-4,-5,36,-1,-2,-3,

%T -4,-5,-6,49,-1,-2,-3,-4,-5,-6,-7,64

%N A002260 * A128064.

%C Row sums = the triangular numbers: (1, 3, 6, 10,...) Row sums of A128077 = A000326, the pentagonal numbers: (1, 5, 12, 22, 35,...)

%F A002260 * A128064 as infinite lower triangular matrices. Retain the right border of A128077 and change the signs of all other terms to (-).

%e First few rows of the triangle are:

%e 1;

%e -1, 4;

%e -1, -2, 9;

%e -1, -2, -3, 16;

%e ...

%Y Cf. A002260, A128064, A128077, A000326.

%K tabl,sign

%O 1,3

%A _Gary W. Adamson_, Feb 14 2007

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Last modified April 20 14:27 EDT 2019. Contains 322310 sequences. (Running on oeis4.)