login
a(n) = A102700(n) - A102342(n).
1

%I #14 Jul 18 2017 00:41:07

%S 1,1,2,3,2,1,3,2,4,4,6,4,4,9,8,7,7,7,7,7,5,2,3,2,2,4,4,7,10,10,9,9,8,

%T 7,5,6,9,7,13,13,13,11,12,14,15,23,16,16,16,10,10,16,13,13,13,13,12,7,

%U 10,7,1,1,1,4,6,5,9,9,13,11,16,13,13,15,13,8,9,8,10,9,10,6,7,7,10,10,11,18

%N a(n) = A102700(n) - A102342(n).

%C a(332) = -1.

%H <a href="/index/Pri#prime_races">Index entries for prime races</a>

%p From _R. J. Mathar_, Apr 25 2010: (Start)

%p A102700 := proc(n) option remember; if n = 1 then 1; else for a from procname(n-1)+1 do if isprime(10*a+9) then return a; end if; end do: end if; end proc:

%p A102342 := proc(n) option remember; if n = 1 then 0; else for a from procname(n-1)+1 do if isprime(10*a+7) then return a; end if; end do: end if; end proc:

%p A139367 := proc(n) A102700(n)-A102342(n) ; end proc: seq(A139367(n),n=1..120) ; (End)

%K sign

%O 1,3

%A _Juri-Stepan Gerasimov_, Jun 09 2008

%E Corrected (a 6 replaced by 7, a 7 by 9, a 13 by 16) and extended by _R. J. Mathar_, Apr 25 2010