

A071219


Numbers m such that the largest prime factor of prime(m) + prime(m+1) equals m.


1




OFFSET

1,1


COMMENTS

a(4), if it exists, is larger than 10^7.
a(4) > 5*10^14, if it exists.  Giovanni Resta, Jul 14 2018


LINKS

Table of n, a(n) for n=1..3.


EXAMPLE

Numbers x such that A006530(A001043(x)) = x.
x = 2 is a term: p(2) + p(3) = 3 + 5 = 8 with largest factor = 2 = x.
x = 3 is a term: p(3) + p(4) = 5 + 7 = 12 with largest factor = 3 = x.
x = 439 is a term: p(439) + p(440) = 3067 + 3079 = 6146 = 2*7*439 = 14x.


MATHEMATICA

DeleteCases[#, 0] &@ MapIndexed[Boole[#1 == First@ #2] First@ #2 &, Map[FactorInteger[Total@ #][[1, 1]] &, Partition[Prime@ Range[10^6], 2, 1]]] (* Michael De Vlieger, Aug 09 2017 *)


CROSSREFS

Cf. A006530, A001043, A071216A071218.
Sequence in context: A097654 A156986 A066849 * A109855 A306370 A128874
Adjacent sequences: A071216 A071217 A071218 * A071220 A071221 A071222


KEYWORD

nonn,bref,more


AUTHOR

Labos Elemer, May 17 2002


EXTENSIONS

Edited by N. J. A. Sloane, Aug 09 2017


STATUS

approved



