login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A278250 Least number with the prime signature of the n-th Wedderburn-Etherington number (A001190). 2
1, 1, 1, 2, 2, 6, 2, 2, 6, 12, 12, 6, 2, 2, 60, 30, 2, 6, 120, 6, 6, 180, 2, 12, 30, 210, 6, 2, 2, 30, 210, 6, 30, 900900, 30, 180, 24, 210, 60060, 210, 13860, 120, 210, 210, 210, 96, 30, 60060, 6126120, 2310, 30, 60, 2310, 2310, 30, 4620, 210, 240, 210, 120, 30, 60, 2, 1260, 30, 30, 2310, 2310, 60, 18480, 30, 2310, 420, 30, 2310, 18480, 30, 3360, 210, 2, 420, 30 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
LINKS
FORMULA
a(n) = A046523(A001190(n)).
PROG
(PARI)
{A001190(n) = local(A); if( n<4, n>0, A = vector(n, i, 1); for( i=4, n, A[i] = sum( j=1, (i-1)\2, A[j] * A[i-j]) + if( i%2, 0, A[i/2] * (A[i/2] + 1)/2)); A[n])}; /* Michael Somos, Mar 25 2006 */
A046523(n) = my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]) \\ Charles R Greathouse IV, Aug 17 2011
for(n=1, 213, write("b278250.txt", n, " ", A278250(n)));
(Scheme) (define (A278250 n) (A046523 (A001190 n)))
CROSSREFS
Cf. also A278258.
Sequence in context: A352892 A126889 A205030 * A357441 A134339 A162299
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 22 2016
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 13 02:00 EDT 2024. Contains 371639 sequences. (Running on oeis4.)