OFFSET
1,1
COMMENTS
Conjecture: the sequence is infinite.
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..2000
EXAMPLE
18913 is in the sequence because:
sum of the distinct prime divisors of 18912 = 2+3+197 = 202;
sum of the distinct prime divisors of 18914 = 2+7+193 = 202.
MAPLE
with(numtheory):for n from 1 to 100000 do:p:=ithprime(n):p1:=p-1: p2:=p+1:t1:=ifactors(p1)[2]; t11 := sum(t1[i][1], i=1..nops(t1)):t2:=ifactors(p2)[2]; t22 := sum(t2[i][1], i=1..nops(t2)):if t11=t22 then printf(`%d, `, p):else fi:od:
MATHEMATICA
Select[Prime[Range[100000]], Total[Transpose[FactorInteger[#-1]][[1]]] == Total[Transpose[FactorInteger[#+1]][[1]]]&] (* Harvey P. Dale, Sep 22 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Dec 30 2011
STATUS
approved