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A296107
Twin prime pairs both of which have the same number of prime digits.
1
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
KEYWORD
nonn,base
AUTHOR
Harvey P. Dale, Dec 04 2017
STATUS
approved