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A027426 Number of distinct products ijk with 0 <= i,j,k <= n. 5
1, 2, 5, 11, 17, 31, 41, 66, 81, 101, 121, 174, 195, 267, 302, 344, 379, 493, 537, 679, 733, 805, 877, 1076, 1131, 1248, 1344, 1451, 1538, 1834, 1910, 2249, 2363, 2516, 2669, 2851, 2941, 3401, 3588, 3790, 3920, 4478, 4625, 5243, 5441, 5655 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000 (first 201 terms from T. D. Noe)

FORMULA

a(n) = A027425(n) + 1. - T. D. Noe, Jan 16 2007

MAPLE

a:=proc(n): nops({seq(seq(seq(i*j*k, k=0..j), j=0..i), i=0..n)}) end: seq(a(n), n=0..50); # Emeric Deutsch, Jan 25 2007

MATHEMATICA

a[n_] := Table[i*j*k, {i, 0, n}, {j, i, n}, {k, j, n}] // Flatten // Union // Length; Table[a[n], {n, 0, 50}] (* Jean-Fran├žois Alcover, Jan 30 2018 *)

PROG

(Haskell)

import Data.List (nub)

a027426 n = length $ nub [i*j*k | i <- [0..n], j <- [0..n], k <- [0..n]]

-- Reinhard Zumkeller, Jan 01 2012

(PARI) pr(n)=my(v=List()); for(i=1, n, for(j=i, n, listput(v, i*j))); Set(v)

a(n)=my(v=pr(n), u=v); for(i=2, n, u=Set(concat(u, v*i))); #u+1 \\ Charles R Greathouse IV, Mar 04 2014

CROSSREFS

Cf. A027384, A027429.

Sequence in context: A023228 A027429 A059987 * A133928 A126204 A091936

Adjacent sequences:  A027423 A027424 A027425 * A027427 A027428 A027429

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified September 26 02:28 EDT 2020. Contains 337346 sequences. (Running on oeis4.)