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A119867 Number of different values assumed by a*b+c*d as a,b,c,d range between 1 and n. 2
1, 6, 14, 25, 40, 57, 79, 103, 132, 165, 201, 239, 283, 329, 379, 434, 493, 554, 620, 688, 762, 839, 918, 1000, 1089, 1182, 1277, 1376, 1480, 1586, 1698, 1811, 1930, 2051, 2175, 2306, 2441, 2577, 2717, 2860, 3010, 3162, 3320, 3479, 3643, 3812, 3983, 4156 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..500

EXAMPLE

a(2)=6 since we can obtain 6 values, i.e., {2, 3, 4, 5, 6, 8}.

MATHEMATICA

Table[Length@Union@Flatten@Table[a*b + c*d, {a, n}, {b, n}, {c, n}, {d, n}], {n, 24}]

CROSSREFS

Cf. A119868.

Sequence in context: A010740 A185594 A095794 * A293400 A026055 A288939

Adjacent sequences:  A119864 A119865 A119866 * A119868 A119869 A119870

KEYWORD

nonn

AUTHOR

Giovanni Resta, May 26 2006

STATUS

approved

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Last modified August 5 22:41 EDT 2021. Contains 346488 sequences. (Running on oeis4.)