A094068 Lessers of twin prime pairs whose greater has a prime prime index.
3, 29, 107, 239, 281, 857, 1061, 1151, 1619, 1667, 1721, 2267, 2339, 2801, 2999, 3167, 3257, 3467, 3557, 4271, 4337, 4547, 4799, 4931, 5279, 5501, 5849, 5867, 6359, 6659, 6689, 7349, 8009, 8219, 8231, 8387, 9857, 10007, 10859, 13001, 13691, 15269, 15971
Offset: 1
Keywords
Examples
107 is the lesser of twin prime pair (107,109) the prime index of 109 (the greater) is 29.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
seq = {}; p = prv = 2; k = 1; Do[p = NextPrime[p]; k++; If[p == prv + 2 && PrimeQ[k], AppendTo[seq, prv]]; prv = p, {10^3}]; seq Select[Partition[Prime[Range[2000]],2,1],#[[2]]-#[[1]]==2&&PrimeQ[PrimePi[ #[[2]]]]&] [[All,1]] (* Harvey P. Dale, Nov 30 2022 *) -
PARI
lista(n) = {forprime(x=2,n, y=prime(x)- 2; if(isprime(y),print1(y",")))}
Extensions
Offset corrected by Amiram Eldar, Dec 27 2019