|
| |
|
|
A083002
|
|
Smallest oblong number having at least n distinct prime divisors.
|
|
3
|
|
|
|
2, 6, 30, 210, 4290, 43890, 510510, 53501910, 1487683470, 64790866140, 530514844860, 126408523110870, 3425113062060690, 660393717163700520, 26657280574571657010, 3448055881024876471350, 308480161111936386482910
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
a(18) <= 32521466098360753728404190. - Donovan Johnson, Oct 05 2011
Oblong numbers are those of the form n(n+1) = A002378(n) = 2*A000217(n).
|
|
|
LINKS
|
Table of n, a(n) for n=1..17.
|
|
|
EXAMPLE
|
a(4)= 210 = 2*3*5*7.
|
|
|
PROG
|
(PARI) {odf(m) = print1(0", "); for(n=1, m, k=1; while(omega(k*(k+1))!=n, k++); print1(k*(k+1)", ")) }
|
|
|
CROSSREFS
|
Cf. A002378, A059958.
Sequence in context: A071290 A185693 A093449 * A192929 A077176 A101178
Adjacent sequences: A082999 A083000 A083001 * A083003 A083004 A083005
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Jason Earls, May 30 2003
|
|
|
EXTENSIONS
|
More terms from Don Reble, Jun 03 2003
a(15)-a(16) from Donovan Johnson, Apr 26 2009
a(17) from Donovan Johnson, Sep 15 2010
|
|
|
STATUS
|
approved
|
| |
|
|
