OFFSET
1,1
EXAMPLE
There are 5 primorial numbers < 10^3: 1, 2, 6, 30 and 210. Thus a(3) = 5.
PROG
(PARI) hashp(n)=prod(i=1, n, prime(i))
a(n)={tot=1; for(k=1, 10^n, if(hashp(k)<10^n, tot++); if(hashp(k)>10^n, break)); return(tot)}
n=1; while(n<100, print1(a(n), ", "); n++)
(PARI) {a(n) = my(p=1, m=10^n); for(k=1, n+3, if(m <= (p *= prime(k)), return(k)))}; /* Michael Somos, Jun 02 2014 */
CROSSREFS
KEYWORD
nonn
AUTHOR
Derek Orr, Jun 01 2014
STATUS
approved