1,1

Harvey P. Dale, Table of n, a(n) for n = 1..1000

If n=6, then (p(6)+r(6))/11=(13+9)/11=2=a(1).

If n=12, then (p(12)+r(12))/11=(37+18)/11=5=a(2).

If n=16, then (p(16)+r(16))/11=(53+24)/11=7=a(3).

If n=34, then (p(34)+r(34))/11=(139+48)/11=17=a(4).

If n=44, then (p(44)+r(44))/11=(193+60)/11=23=a(5), etc.

A141468 := proc(n) option remember ; if n = 1 then 0; else for a from procname(n-1)+1 do if not isprime(a) then RETURN(a) ; fi; od: fi: end: A000040 := proc(n) ithprime(n) ; end: for n from 1 to 6000 do c := A000040(n)+A141468(n) ; if c mod 11 = 0 then if isprime(c/11) then printf("%d, ", c/11) ; fi; fi; od: # R. J. Mathar, Nov 03 2008

Module[{nn=50000, pr, np, len}, pr=Select[Range[nn], PrimeQ]; np=Complement[ Range[0, nn], pr]; len=Min[Length[pr], Length[np]]; Select[Total[#]/11&/@ Thread[ {Take[pr, len], Take[np, len]}], PrimeQ]] (* Harvey P. Dale, Jun 27 2020 *)

Cf. A000040, A141468.

Sequence in context: A307452 A066028 A066039 * A318731 A256062 A303677

Adjacent sequences: A142338 A142339 A142340 * A142342 A142343 A142344

Juri-Stepan Gerasimov, Sep 19 2008

3 replaced by 5, 241 and 257 inserted and extended by R. J. Mathar, Nov 03 2008

approved