Search: id:A070027
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%I A070027
%S A070027 2,3,5,7,11,23,29,41,43,47,61,83,101,113,131,137,151,173,191,223,227,
%T A070027 241,263,281,311,313,317,331,353,401,421,443,461,599,601,641,797,821,
%U A070027 887,911,977,1013,1019,1031,1033,1051,1091,1103,1109,1123,1163,1181,1213
%N A070027 Prime numbers whose initial, all intermediate and final iterated sums 
               of digits are primes.
%C A070027 Subsequence of A046704 ; actually, exactly those numbers for which the 
               orbit under A007953 is a subset of A046704. [From M. F. Hasler (MHasler(AT)univ-ag.fr), 
               Jun 28 2009]
%e A070027 599 is a term because 599, 5+9+9=23 and 2+3=5 are all prime. 2999 is 
               a term because 2999, 2+9+9+9=29, 2+9=11 and 1+1=2 are all prime. 
               See A062802 and A070026 for related comments.
%p A070027 P:=proc(i) local a,k,n,w; for n from 1 by 1 to i do a:=ithprime(n); while 
               isprime(a) and floor(a/10)>0 do w:=0; k:=a; while k>0 do w:=w+k-(trunc(k/
               10)*10); k:=trunc(k/10); od; a:=w; od; if isprime(a) then print(ithprime(n)); 
               fi; od; end: P(1000); - Paolo P. Lava (ppl(AT)spl.at), Jul 30 2008
%o A070027 (PARI) isA070027(n)={ while(isprime(n), n<9 && return(1); n=vector(#n=eval(Vec(Str(n))),
               i,1)*n~)} \\ [From M. F. Hasler (MHasler(AT)univ-ag.fr), Jun 28 2009]
%Y A070027 Cf. A070026 (a supersequence), subsequences: A062802, A070028, A070029.
%Y A070027 Sequence in context: A046704 A089392 A089695 this_sequence A156658 A118723 
               A118721
%Y A070027 Adjacent sequences: A070024 A070025 A070026 this_sequence A070028 A070029 
               A070030
%K A070027 base,easy,nonn
%O A070027 0,1
%A A070027 Rick L. Shepherd (rshepherd2(AT)hotmail.com), Apr 14 2002

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