OFFSET
1,1
COMMENTS
Twinmorial numbers are the partial products of twin primes. Sum of reciprocals = 0.08756985926348207565388288916..
The next term (a(14)) has 174 digits. - Harvey P. Dale, Mar 30 2013
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..19
FORMULA
Twins 3*5 = 15 = p+2. p=13.
MATHEMATICA
Select[#/2-2&/@Rest[FoldList[Times, 1, Prime[Range[100]]]], PrimeQ] (* Harvey P. Dale, Mar 30 2013 *)
PROG
(PARI) twimorial(n) = { s=0; p=3; forprime(x=5, n, if(isprime(x-2), c1++); p=p*x; if(isprime(p-2), print1(p-2", "); c2++; s+=1.0/(p-2); ) ); print(); print(s) }
(PARI) v=[]; pr=1; forprime(p=3, 2357, pr*=p; if(ispseudoprime(pr-2), v=concat(v, pr-2))) \\ Charles R Greathouse IV, Feb 14 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
Cino Hilliard, Oct 21 2003
EXTENSIONS
Description corrected by Hugo Pfoertner, Jun 25 2004
One more term (a(13)) added by Harvey P. Dale, Mar 30 2013
STATUS
approved