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%I #17 Feb 10 2019 03:43:03
%S 2,11,13,17,19,29,31,37,47,53,67,71,73,83,89,101,103,107,109,127,137,
%T 139,157,163,173,179,181,191,193,197,199,211,227,229,233,251,263,269,
%U 271,281,283,307,317,337,353,359,373,379,389,397,409,431,433,443
%N Primes with digital root 1, 2, 4 or 8.
%C Primes which under repeated summation of digits eventually reach 1, 2, 4 or 8.
%H Nathaniel Johnston, <a href="/A166849/b166849.txt">Table of n, a(n) for n = 1..10000</a>
%e The prime 229 is a member since 229 -> 13 -> 4.
%p A166849 := proc(n) option remember: local k: if(n=1)then return 2:fi: k:=nextprime(procname(n-1)): do if((k-1) mod 9 in {0,1,3,7})then return k: fi: k:=nextprime(k): od: end: seq(A166849(n), n = 1..54); # _Nathaniel Johnston_, May 04 2011
%t dr[n_]:=NestWhile[Total[IntegerDigits[#]]&,n,#>9&]; Select[Prime[Range[ 100]], MemberQ[{1,2,4,8},dr[#]]&] (* _Harvey P. Dale_, Oct 25 2011 *)
%Y Cf. A010888.
%K nonn,base,easy
%O 1,1
%A _Alexander R. Povolotsky_, Oct 21 2009
%E Edited by _N. J. A. Sloane_ and _Zak Seidov_, Oct 23 2009
%E More terms a(11)-a(51) from _Vincenzo Librandi_, Oct 24 2009
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