OFFSET
1,1
COMMENTS
n = 10^6*p+10^4*q+10^2*r+s, with primes p,q,r,s, 98>p>q>r>s>10.
There are 722 such primes from 29231311,37231913,37311913 to
97897931,97897973,97898347.
MATHEMATICA
pr2={97, 89, 83, 79, 73, 71, 67, 61, 59, 53, 47, 43, 41, 37, 31, 29, 23, 19, 17, 13, 11};
k=4; ssk=Subsets[pr2, {k}]; Le=Binomial[21, k];
Reap[Do[If[PrimeQ[fd=FromDigits[Flatten[IntegerDigits/@ssk[[i]]]]], Sow[fd]], {i, Le}]][[2, 1]]
CROSSREFS
KEYWORD
base,fini,full,nonn
AUTHOR
Zak Seidov, Nov 28 2009
STATUS
approved