A350826 Number of prime sextuplets with n-digit initial term (A022008).
1, 1, 0, 0, 3, 0, 13, 64, 235, 1296, 7013, 41782, 253420, 1607418, 10520883, 70785653, 488096844
Offset: 1
Examples
For n = 1, p = 7 is the only 1-digit prime to be the initial term of a prime sextuplet, (7, 11, 13, 17, 19, 23), hence a(1) = 1. For n = 2, p = 97 is the only 2-digit prime to be the initial term of a prime sextuplet, (97, 101, 103, 107, 109, 113), whence a(2) = 1. For n = 3 and n = 4, there is no n-digit prime to be the initial term of a prime sextuplet, so a(n) = 0. For n = 5, {16057, 19417, 43777} are the only 5-digit primes which are initial members of a prime sextuplet, therefore a(5) = 3.
Links
- Norman Luhn, PI_6(10^n)
Crossrefs
Programs
Formula
a(n) = # { p in A022008 | 10^(n-1) < p < 10^n }.
Extensions
a(10)-a(12) from David A. Corneth, Jan 17 2022
a(13)-a(17) from Hugo Pfoertner, Jan 21 2022
Comments