A158571 - OEIS

%I #11 Apr 03 2023 10:36:11

%S 13,17,31,53,71,103,107,211,233,251,431,503,521,701,1021,1061,1151,

%T 1201,1223,1511,1601,2011,2141,2213,2411,3001,3023,3041,3203,3221,

%U 4013,4211,5003,5021,6011,6101,7001,10007,10061,10111,10133,10151,10223,10313

%N Primes whose digit sum is a single-digit nonprime.

%C It is interesting to observe that it is hard to find (I found none) primes whose digit sum is 6. On the contrary, it is easier to find primes whose digit sum is 8.

%C The digit sum 6 does not occur here because a number with digit sum 6 is divisible by 3 and therefore not prime. - _R. J. Mathar_, Mar 26 2009

%H Robert Israel, <a href="/A158571/b158571.txt">Table of n, a(n) for n = 1..10000</a>

%H Chris Caldwell, <a href="https://t5k.org/lists/small/1000.txt">The First 1,000 Primes</a>

%F Union of A062339 and A062343. - _R. J. Mathar_, Mar 26 2009

%e 1061 is a prime whose digit sum is 8, which is a single-digit nonprime.

%p for i from 1 to 8 do if member(i,[1,3,7]) then S[1,i]:= {i} else S[1,i]:= {} fi od:

%p for d from 2 to 5 do

%p   for x from 1 to 8 do

%p     S[d,x]:= {};

%p     for y from 0 to x-1 do

%p       S[d,x]:= S[d,x] union map(t -> 10^(d-1)*y + t, S[d-1,x-y])

%p od od od:

%p select(isprime, S[5,4] union S[5,8]); # _Robert Israel_, Apr 14 2021

%Y Cf. A158217.

%K base,nonn

%O 1,1

%A _Parthasarathy Nambi_, Mar 21 2009

%E Extended by _R. J. Mathar_, Mar 26 2009