A074953 Numbers equidistant from consecutive twin prime pairs.

5, 9, 15, 24, 36, 51, 66, 87, 105, 123, 144, 165, 186, 195, 213, 234, 255, 276, 297, 330, 384, 426, 447, 492, 546, 585, 609, 630, 651, 735, 816, 825, 843, 870, 951, 1026, 1041, 1056, 1077, 1122, 1191, 1254, 1284, 1296, 1311, 1374, 1440

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = (A006512(n+1) + A001359(n))/2. - Michel Marcus, Jul 26 2015

Example

The twin prime pairs are (3,5), (5,7), (11,13), (17,19), etc. a(n) is equidistant from the higher prime in the n-th pair and the lower prime in the (n+1)th pair. E.g., a(2) is the mean of 7 and 11, which is 9.

Mathematica

t = Select[ Prime@ Range@ 250, PrimeQ[# + 2] &]; Most@ t + Differences[t]/2 + 1 (* Robert G. Wilson v, Jul 26 2015 *)

Prog

(PARI) lista(nn) = {forprime (p=2, nn, q = nextprime(p+1); if (q==p+2, forprime (pp=q, nn, if (nextprime(pp+1) == pp+2, print1((q+pp)/2, ", "); break; ); ); ); ); } \\ Michel Marcus, Jul 26 2015

Crossrefs

Cf. A001359, A006512.

Sequence in context: A315083 A294020 A025005 * A023498 A256343 A210289

Adjacent sequences: A074950 A074951 A074952 * A074954 A074955 A074956

Keyword

nonn

Author

Neil Fernandez, Oct 05 2002

Status

approved