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A227800 Number of different values the product p*q can have where p >= 1, q >= 1 with p+q < n. 1
0, 0, 1, 2, 4, 5, 8, 10, 13, 16, 19, 21, 26, 29, 34, 39, 44, 48, 53, 58, 65, 71, 78, 83, 91, 97, 104, 111, 118, 124, 134, 141, 150, 158, 167, 176, 186, 194, 204, 213, 224, 232, 245, 254, 267, 278, 290, 301, 315, 328, 339, 351, 366, 376, 391, 404, 419, 432, 446 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Game played often with n = 10.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..2000

MAPLE

A227800 := proc(n)

    local s, p, q ;

    s := {} ;

    for p from 1 to iquo(n-1, 2) do

    for q from p to n-1-p do

            s := s union {p*q} ;

    end do:

    end do:

    nops(s) ;

end proc:

seq(A227800(n), n=1..120) ; # R. J. Mathar, Nov 24 2013

MATHEMATICA

A227800[n_] := Module[{s, p, q}, s = {}; For[p = 1, p <= Quotient[n-1, 2], p++, For[q = p, q <= n-1-p, q++, s = s ~Union~ {p*q}]] ; Length[s]]; Table[A227800[n], {n, 1, 120}] (* Jean-Fran├žois Alcover, Feb 27 2014, after R. J. Mathar *)

CROSSREFS

Sequence in context: A072437 A115793 A076614 * A144876 A337483 A239517

Adjacent sequences:  A227797 A227798 A227799 * A227801 A227802 A227803

KEYWORD

nonn

AUTHOR

Henry W. Gould, Sep 23 2013

STATUS

approved

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Last modified April 21 14:07 EDT 2021. Contains 343154 sequences. (Running on oeis4.)