A282690 a(n) is the smallest number m, such that m+n is the next prime and m-n is the previous prime.

4, 5, 26, 93, 144, 53, 120, 1839, 532, 897, 1140, 211, 2490, 2985, 4312, 5607, 1344, 9569, 30612, 19353, 16162, 15705, 81486, 16787, 31932, 19635, 35644, 82101, 44322, 43361, 34092, 89721, 162176, 134547, 173394, 31433, 404634, 212739, 188068, 542643, 265662

Offset

1,1

Links

Daniel Suteu, Table of n, a(n) for n = 1..100

Example

For n = 6, a(6) = 53, because the next prime after 53 is 59 and the previous prime before 53 is 47, where both have an equal distance of 6 from 53, which is the smallest number with this property.

Mathematica

Table[k = 1; While[Nand[k - n == NextPrime[k, -1], k + n == NextPrime@ k], k++]; k, {n, 41}] (* Michael De Vlieger, Feb 20 2017 *)

Prog

(Perl)
use ntheory qw(:all);
for (my $k = 1 ; ; ++$k) {
    for (my $n = 1 ; ; ++$n) {
        my $p = prev_prime($n) || next;
        my $q = next_prime($n);
        if ($n-$p == $k and $q-$n == $k) {
            printf("%s %s\n", $k, $n);
            last;
        }
    }
}

Crossrefs

Cf. A087378, A087711, A282687.

Sequence in context: A144053 A084465 A056200 * A282687 A153429 A270217

Adjacent sequences: A282687 A282688 A282689 * A282691 A282692 A282693

Keyword

nonn

Author

Daniel Suteu, Feb 20 2017

Status

approved