A089699 - OEIS

%I #7 Aug 13 2017 21:42:38

%S 1,2,4,6,12,16,22,28,36,52,58,66,82,112,126,136,156,162,166,192,198,

%T 232,256,268,292,312,316,346,348,352,366,372,388,396,438,486,556,562,

%U 568,576,586,612,616,652,658,682,732,756,768,786,796,826,838,856,862

%N Numbers n with property that n + 1 as well as the (product of digits of n) + 1 are primes.

%H Harvey P. Dale, <a href="/A089699/b089699.txt">Table of n, a(n) for n = 1..1000</a>

%p for n from 1 to 150 do p:=ithprime(n): m:=mul(j,j=convert(p-1,base,10)): if isprime(m+1) then printf("%d, ",p-1) fi od: # C. Ronaldo

%t Select[Prime[Range[200]]-1,PrimeQ[Times@@IntegerDigits[#]+1]&] (* _Harvey P. Dale_, Apr 09 2014 *)

%Y Cf. A089700, A089701.

%K base,nonn

%O 1,2

%A _Amarnath Murthy_, Nov 10 2003

%E Corrected and extended by C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 25 2004