A357052 Distance from 10^n to the next prime triplet.
4, 1, 1, 87, 267, 357, 33, 451, 2011, 2821, 10687, 2497, 5073, 5557, 15243, 7147, 7357, 7197, 6627, 9157, 26317, 25833, 39207, 56067, 6667, 32937, 70561, 106533, 597, 28503, 19167, 74551, 301711, 6747, 246871, 223353, 63057, 75183, 48513, 61323, 16107, 554287, 160141, 29821, 220711, 49441
Offset: 0
Examples
(11, 13, 17) and (101, 103, 107) are the smallest 2-digit and 3-digit prime triplets, at distance a(1) = a(2) = 1 from 10^1 and 10^2, respectively. (1087, 1091, 1093) is the smallest 4-digit prime triplet, at distance a(3) = 87 from 10^3. a(6999) = 1141791245437 is the distance from 10^6999 to the smallest 7000 digit prime triplet, of the form (p, p+2, p+6).
Links
- Michael S. Branicky, Table of n, a(n) for n = 0..216
- Norman Luhn, smallest 7000 digit prime triplet, primenumberstheory mailing list at groups.io, Sep 14 2022
Crossrefs
Programs
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Maple
f:= proc(n) local p; for p from 10^n + 1 by 2 do if p mod 3 = 1 then if isprime(p) and isprime(p+4) and isprime(p+6) then return p-10^n fi elif p mod 3 = 2 and isprime(p) and isprime(p+2) and isprime(p+6) then return p-10^n fi od; end proc: f(0):= 4: map(f, [$0..45]); # Robert Israel, Sep 15 2022 A357052 := proc(n) local p,q,r; p,q,r := 10^n,0,0; while p-r <> 6 do p,q,r := nextprime(p+1),p,q; od; r-10^n; end; # M. F. Hasler, Sep 15 2022
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PARI
A357052(n,q=-9,r=-9)=forprime(p=10^n,,p-r<7 && return(r-10^n);[q,r]=[p,q])
Formula
a(n) = min{ k>0 | 10^n + k + [0, 6] contains 3 primes }.
a(n) = min A007529 ∩ [10^n, oo) for n > 0.
Comments