A060210 Largest prime factor of 1+smaller term of twin primes.

2, 3, 3, 3, 5, 7, 5, 3, 17, 3, 23, 5, 5, 3, 11, 19, 5, 5, 47, 13, 29, 7, 3, 11, 29, 19, 5, 103, 107, 11, 5, 137, 23, 13, 7, 17, 43, 7, 59, 13, 3, 41, 71, 43, 31, 11, 17, 11, 19, 31, 67, 5, 139, 283, 41, 149, 13, 313, 23, 13, 37, 13, 347, 29, 11, 71, 17, 373, 7, 11, 13, 397, 17

Offset

1,1

Comments

Also: Largest prime factor of the average, or the sum, of twin prime pairs. - M. F. Hasler, Jan 03 2011

Links

T. D. Noe, Table of n, a(n) for n = 1..10000

Example

101 is the 9th lesser twin, 102 = 2*3*17, and its max p factor is 17=a(9).

Mathematica

FactorInteger[1+#][[-1, 1]]&/@Select[Partition[Prime[Range[500]], 2, 1], #[[2]]- #[[1]]==2&][[All, 1]] (* Harvey P. Dale, Jan 16 2017 *)

Prog

(PARI) p=3; for(n=1, 1e3, until(o+2==p, p=nextprime(2+o=p)); print1(vecmax(factor(p-1)[, 1])", "))  \\ M. F. Hasler, Jan 03 2011

Crossrefs

Cf. A001359, A001454, A002822, A059960, A027856.

Sequence in context: A029065 A263253 A162157 * A260460 A000025 A036020

Adjacent sequences: A060207 A060208 A060209 * A060211 A060212 A060213

Keyword

nonn

Author

Labos Elemer, Mar 20 2001

Status

approved