A120384 Isolated primes: geometric mean of distances of a prime to neighboring primes sets record.
3, 5, 7, 23, 53, 89, 113, 211, 1259, 1327, 1847, 2179, 2503, 5623, 14107, 19661, 24281, 38501, 58831, 268343, 396833, 1272749, 2198981, 3863107, 4411963, 4958131, 5102953, 7950001, 8917523, 10938023, 12623189, 22440841, 24662467, 32616223
Offset: 1
Keywords
Examples
a(4) = 23 because the distance (geometric mean) to its neighbors (19 and 29) equals = sqrt(4*6) = 4.8989. No smaller prime is more isolated. The next more isolated prime a(5) is 53.
Links
- Ken Takusagawa, Table of n, a(n) for n = 1..54
Crossrefs
Cf. A096265.
Programs
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PARI
lista(nn) = {d = 0; p = 1; q = 2; r = 3; for (i=1, nn, p = q; q = r; r = nextprime(r+1); if ((nd = (q-p)*(r-q)) > d, print1(q, ", "); d = nd;););} \\ Michel Marcus, Jun 12 2013
Extensions
Offset corrected and a(22)-a(34) added by Donovan Johnson, May 23 2010
Comments