A158906 -id:A158906 - cp's OEIS frontend

A158907 Row sums of triangle A158906.

1, 3, 4, 6, 6, 9, 8, 11, 11, 13, 12, 17, 14, 17, 18, 20, 18, 23, 20, 25, 24, 25, 24, 31, 27, 29, 30, 33, 30, 37, 32, 37, 36, 37, 38, 44, 38, 41, 42, 47, 42, 49, 44, 49, 50, 49, 48, 57, 51, 55, 54, 57, 54, 61, 58, 63, 60, 61, 60

Offset: 1

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Gary W. Adamson and Mats Granvik, Mar 29 2009

nonn
easy

This is the number of pairs of positive integers (i,j) such that i*j = n or i+j = n (where (2,2) is double-counted as both 2+2=4 and 2*2=4.) - Peter Kagey, Oct 02 2020

			a(4) = 6 = (4 + 1 + 0 + 1).

Cf. A032741, A158906.

A158906 := proc(n,k)
    add( A158821(n-1,j-1)*A051731(j,k),j=k..n) ;
end proc:
A158907 := proc(n)
    add(A158906(n,k),k=1..n) ;
end proc:
seq(A158907(n),n=1..62) ; # R. J. Mathar, Jan 08 2015

a(n) = Sum_{k=1..n} A158906(n,k).
a(p) = p + 1 for prime p. [corrected by Ruediger Jehn, Dec 25 2020]
a(n) = A032741(n) + n. - R. J. Mathar, Jan 08 2015
a(n) = Sum_{i=1..n} floor(n/i)-floor((n-1)/(i+1)). - Wesley Ivan Hurt, Sep 13 2017

cp's OEIS Frontend

A158907 Row sums of triangle A158906.

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