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 A164291 a(n) = p is the first twin prime (p, p+2) for which p+1 has n prime factors (n>=2, multiplicity counted). 3
 3, 11, 59, 71, 239, 191, 2111, 1151, 14591, 26111, 15359, 139967, 138239, 675839, 2101247, 737279, 4866047, 786431, 22118399, 36175871, 194641919, 63700991, 138412031, 169869311, 1321205759, 11123294207, 16357785599, 4076863487, 25165823999, 10871635967 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS a(3)-a(6) are the first elements of A060213, A102168, A164289, A164290 respectively with n=3,4,5,6 (prime factors in the middle number). This gives the first p with (p,p+2) twin primes and Omega(p+1)=n with n>=2 (n=1 is impossible). LINKS Donovan Johnson, Table of n, a(n) for n = 2..200 EXAMPLE a(7)=191 because in (191, 192, 193) we have Omega(192)=Omega(2*2*2*2*2*2*3)=7 and 191, 193 are twin primes. The sequence oscillates and here we see that a(7)

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Last modified March 28 13:18 EDT 2023. Contains 361585 sequences. (Running on oeis4.)