A168515 Primes n that are concatenation of four 2-digit primes in decreasing order.

29231311, 37231913, 37311913, 41231713, 41291311, 41291713, 41292311, 41292319, 41311913, 41312911, 41312923, 41372311, 41372911, 43191311, 43231711, 43311713, 43311911, 43371917, 43412911, 47231311, 47231711

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.

Links

Table of n, a(n) for n=1..21.

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

Cf. A168499, A168500, A168513.

Sequence in context: A198172 A176141 A105013 * A287384 A107619 A320723

Adjacent sequences: A168512 A168513 A168514 * A168516 A168517 A168518

Keyword

base,fini,full,nonn

Author

Zak Seidov, Nov 28 2009

Status

approved