OFFSET
0,1
COMMENTS
LINKS
Dana Jacobsen, Table of n, a(n) for n = 0..59 (first 45 terms from Robert G. Wilson v)
FORMULA
a(n) = A001358(2^n).
EXAMPLE
a(0)=4 is the first semiprime;
a(1)=6 is the 2nd semiprime;
a(16)=295003 is the 65536th semiprime.
PROG
(PARI) SP( n=0 /*tested number*/, c=0 /*count of semiprimes*/, step=2)={ local( l=c+!c ); /* negative/positive step means arithmetic/geometric progression of output threshold l */ until( 0, until(l<=c++, until(bigomega(n+=1)==2, )); print1(/*c ":" */ n ", "); if(step>0, l*=step, l-=step))}
(Perl) use ntheory ":all"; my($i, $g)=(0, 0); forsemiprimes { print $g++, " $_\n" if ++$i == 1<<$g; } 10**8; # Dana Jacobsen, Sep 10 2018
(Perl) use ntheory ":all"; print "$_ ", nth_semiprime(1<<$_), "\n" for 0..40; # Dana Jacobsen, Oct 08 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Oct 04 2007
EXTENSIONS
a(23)-a(28) from Donovan Johnson, Nov 11 2008
a(29)-a(33) from Max Alekseyev, May 07 2010
STATUS
approved