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 A027384 Number of distinct products ij with 0 <= i, j <= n. 10
 1, 2, 4, 7, 10, 15, 19, 26, 31, 37, 43, 54, 60, 73, 81, 90, 98, 115, 124, 143, 153, 165, 177, 200, 210, 226, 240, 255, 268, 297, 309, 340, 355, 373, 391, 411, 424, 461, 481, 502, 518, 559, 576, 619, 639, 660, 684, 731, 748, 779, 801, 828, 851, 904, 926, 957, 979, 1009, 1039 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS a(n) = A027420(n,0) = A027420(n,n). - Reinhard Zumkeller, May 02 2014 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 (terms 0..1000 from T. D. Noe) R. P. Brent, C. Pomerance, D. Purdum, and J. Webster, Algorithms for the multiplication table, arXiv:1908.04251 [math.NT], 2019-2021. FORMULA For prime p, a(p) = a(p - 1) + p. - David A. Corneth, Jan 01 2019 MAPLE A027384 := proc(n)     local L, i, j ;     L := {};     for i from 0 to n do         for j from i to n do             L := L union {i*j};         end do:     end do:     nops(L); end proc: # R. J. Mathar, May 06 2016 MATHEMATICA u = {}; Table[u = Union[u, n*Range[0, n]]; Length[u], {n, 0, 100}] (* T. D. Noe, Jan 07 2012 *) PROG (Haskell) import Data.List (nub) a027384 n = length \$ nub [i*j | i <- [0..n], j <- [0..n]] -- Reinhard Zumkeller, Jan 01 2012 (PARI) a(n) = {my(s=Set()); for (i=0, n, s = setunion(s, Set(vector(n+1, k, i*(k-1)))); ); #s; } \\ Michel Marcus, Jan 01 2019 CROSSREFS Equals A027424 + 1, n>0. Cf. A027417, A027427, A027425. Sequence in context: A276164 A306221 A095116 * A022939 A036702 A007983 Adjacent sequences:  A027381 A027382 A027383 * A027385 A027386 A027387 KEYWORD nonn,easy,changed AUTHOR Fred Schwab (fschwab(AT)nrao.edu) STATUS approved

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Last modified May 17 12:43 EDT 2021. Contains 343971 sequences. (Running on oeis4.)