A296107 Twin prime pairs both of which have the same number of prime digits.

3, 5, 5, 7, 29, 31, 809, 811, 1229, 1231, 1289, 1291, 2129, 2131, 2309, 2311, 2729, 2731, 2789, 2791, 2999, 3001, 3299, 3301, 3329, 3331, 3389, 3391, 3929, 3931, 4229, 4231, 5009, 5011, 5099, 5101, 6089, 6091, 6299, 6301, 6689, 6691, 7589, 7591, 8009, 8011

Offset

1,1

Comments

This was essentially the original definition of A158284 but the given terms to that sequence did not match this definition.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Example

3929 and 3931 are twin primes and both have two prime digits.

Mathematica

Select[Partition[Prime[Range[2000]], 2, 1], #[[2]]-#[[1]]==2 && Count[ IntegerDigits[#[[1]]], _?PrimeQ]==Count[IntegerDigits[#[[2]]], _?PrimeQ]&]//Flatten

Prog

(PARI) ct(n)=my(d=digits(n)); sum(i=1, #d, isprime(d[i]))
do(lim)=my(v=List(), p=3); forprime(q=5, lim+2, if(q-p==2 && ct(p)==ct(q), listput(v, p); listput(v, q)); p=q); Vec(v) \\ Charles R Greathouse IV, Dec 05 2017

Crossrefs

Cf. A158284.

Sequence in context: A226540 A309572 A366679 * A158331 A197286 A019632

Adjacent sequences: A296104 A296105 A296106 * A296108 A296109 A296110

Keyword

nonn,base

Author

Harvey P. Dale, Dec 04 2017

Status

approved