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 A326230 Least k > 1 such that k^n is a twin rank (cf. A002822: 6*k^n +- 1 are twin primes). 7
 2, 5, 28, 70, 2, 1820, 110, 1850, 2520, 220, 2023, 9415, 647, 2880, 2562, 3895, 2, 51240, 525, 3750, 147, 2350, 355, 4480, 2588, 3370, 38157, 1185, 1473, 12530, 4338, 1540, 1988, 535, 102, 22606, 13773, 18895, 16373, 2635, 20428, 76300, 23037, 29005, 11078 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Dinculescu observes that when k^2 > 1 is a twin rank (i.e., in A002822) then 5 | k (k is divisible by 5), and if k^3 is a twin rank, then 7 | k; cf. A326232 & A326234. It is unknown whether there are other pairs (a, b) such that a | n whenever n^b > 1 is a twin rank. (Of course 2 | b => 5 | a and 3 | b => 7 | a, so we aren't interested in pairs (a, b) which are consequence of this.) LINKS Table of n, a(n) for n=1..45. A. Dinculescu, On the Numbers that Determine the Distribution of Twin Primes, Surveys in Mathematics and its Applications, 13 (2018), 171-181. PROG (PARI) a(n)=for(k=2, oo, ispseudoprime(6*k^n-1)&&ispseudoprime(6*k^n+1)&&return(k)) CROSSREFS Cf. A326231 .. A326236, A002822. Sequence in context: A025170 A151775 A286879 * A095159 A047132 A364112 Adjacent sequences: A326227 A326228 A326229 * A326231 A326232 A326233 KEYWORD nonn AUTHOR M. F. Hasler and Antonie Dinculescu, Jun 16 2019 STATUS approved

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Last modified July 18 21:02 EDT 2024. Contains 374388 sequences. (Running on oeis4.)