A103129 Least k such that 10^n + k - 1 is the first of a pair of twin primes.

2, 2, 20, 8, 152, 38, 140, 38, 8, 278, 818, 62, 1268, 98, 2372, 1550, 20, 620, 98, 392, 410, 650, 5528, 2732, 560, 950, 428, 602, 2798, 1682, 7190, 2450, 6752, 7598, 8420, 16880, 872, 5570, 10328, 16112, 2132, 6122, 23330, 5180, 4250, 2642, 2258, 3998, 8282, 18308, 7538, 41348

Offset

1,1

Links

Table of n, a(n) for n=1..52.

Mathematica

a[n_]:=Take[Select[Range[50000], PrimeQ[10^n+#-1]&&PrimeQ[10^n+#+1]&], 1][[1]]; Table[a[n], {n, 52}]  (* James C. McMahon, Jan 23 2024 *)

Prog

(PARI) a(n) = my(k=1); while (!isprime(10^n + k - 1) || !isprime(10^n + k + 1), k++); k; \\ Michel Marcus, Jan 24 2024

Crossrefs

Sequence in context: A093777 A326177 A370709 * A322898 A009340 A053593

Adjacent sequences: A103126 A103127 A103128 * A103130 A103131 A103132

Keyword

nonn

Author

Pierre CAMI, Mar 17 2005

Extensions

Corrected and extended by Don Reble, Mar 18 2005

a(49)-a(52) from James C. McMahon, Jan 27 2024

Status

approved