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A074953
Numbers equidistant from consecutive twin prime pairs.
3
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
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
Sequence in context: A315083 A294020 A025005 * A023498 A256343 A210289
KEYWORD
nonn
AUTHOR
Neil Fernandez, Oct 05 2002
STATUS
approved