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A226959
a(0)=1 and a(n)=prime(n)*lcm(prime(n)-1, a(n-1)) for n > 0.
1
1, 2, 6, 60, 420, 4620, 60060, 4084080, 232792560, 5354228880, 155272637520, 4813451763120, 178097715235440, 7302006324653040, 313986271960080720, 14757354782123793840, 782139803452561073520, 46146248403701103337680, 2814921152625767303598480
OFFSET
0,2
COMMENTS
A226957(a(n)) = n.
Is this a subset of A168264? - Ralf Stephan, Jul 04 2013
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 0..347
MATHEMATICA
a[0]=1; a[n_]:= a[n]=Prime[n]*LCM[a[n - 1], Prime[n] -1];
Table[a[i], {i, 1, 18}]
PROG
(PARI) a(n)=if(n, my(v=primes(n), e=vector(n, i, 1), f, j); forprime(p=2, v[n], f=factor(p-1); for(i=1, #f~, if(f[i, 2]>1, j=primepi(f[i, 1]); e[j]=max(e[j], f[i, 2])))); prod(i=1, n, v[i]^e[i]), 1) \\ Charles R Greathouse IV, Jun 28 2013
CROSSREFS
Sequence in context: A102290 A025540 A334224 * A083135 A056604 A376515
KEYWORD
nonn
AUTHOR
STATUS
approved