login
A083001
Smallest oblong number having n prime divisors (with multiplicity).
1
2, 6, 12, 56, 72, 240, 1056, 4160, 4032, 50400, 65280, 1639680, 262656, 15748992, 40953600, 104867840, 16773120, 205535232, 1073774592, 4294901760, 52613120000, 32480870400, 233605472256, 68719214592, 4398044413952
OFFSET
1,1
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..40 (terms < 2*10^21)
EXAMPLE
a(4) = 56 = 2*2*2*7.
MATHEMATICA
a={}; k=1; For[n=1, n<=25, n++, While[PrimeOmega[k(k+1)]!=n, k++]; AppendTo[a, k(k+1)]]; a (* Stefano Spezia, Jan 01 2023 *)
PROG
(PARI) {ondf(m) = for(n=1, m, k=1; while(bigomega(k*(k+1))!=n, k++); print1(k*(k+1)", ")) }
CROSSREFS
Sequence in context: A369330 A152873 A175810 * A285079 A119862 A111936
KEYWORD
nonn
AUTHOR
Jason Earls, May 30 2003
EXTENSIONS
More terms from Don Reble, Jun 03 2003
a(0) = 0 removed by Stefano Spezia, Jan 04 2023
STATUS
approved