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A158907 Row sums of triangle A158906. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
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
LINKS
FORMULA
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
EXAMPLE
a(4) = 6 = (4 + 1 + 0 + 1).
MAPLE
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
CROSSREFS
Sequence in context: A284061 A162625 A033095 * A338281 A338723 A175708
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson and Mats Granvik, Mar 29 2009
STATUS
approved

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Last modified March 29 00:26 EDT 2024. Contains 371264 sequences. (Running on oeis4.)