A341706 - OEIS

A341706

Row 2 of semigroup multiplication table shown in A341317 and A341318.

0, 2, 7, 8, 16, 17, 18, 29, 30, 31, 32, 46, 47, 48, 49, 50, 67, 68, 69, 70, 71, 72, 92, 93, 94, 95, 96, 97, 98, 121, 122, 123, 124, 125, 126, 127, 128, 154, 155, 156, 157, 158, 159, 160, 161, 162, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 232, 233, 234

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OFFSET

0,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..10000

MAPLE

t:= n-> n*(n-1)/2:

f:= n-> ceil((sqrt(1+8*n)-1)/2):

g:= n-> (x-> [x, n-t(x)][])(f(n)):

a:= n-> (h-> t(h[1]*h[3])+h[2]*h[4])(map(g, [n, 2])):

seq(a(n), n=0..60); # Alois P. Heinz, Feb 17 2021

CROSSREFS