Search: id:A117477
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%I A117477
%S A117477 131,263,1039,1091,1301,1361,1433,2221,2441,2591,2663,2719,2803,3433,
%T A117477 3631,4153,4357,4397,5507,5701,5741,5927,6311,6353,6553,6737,6827,6971,
%U A117477 7013,7213,7411,7523,7741,8821,9103,11173,11353,11731,11821,12277,12347
%N A117477 Primes whose SOD and that of their indices are both prime and equal (indices 
               may not be prime, but their SOD must be prime).
%C A117477 "SOD" = "sum of digits".
%C A117477 This sequence is a subset of A033548, the difference being that this 
               sequence requires prime SODs.
%F A117477 Find primes whose indices, when SODs are computed, are both prime and 
               SOD(i) = SOD(p)
%e A117477 a(3) = 1039, the 175th prime. Both the SOD of the index and the prime 
               are prime and equal: 13 = 13.
%o A117477 UBASIC 20 'SOD prime index and SOD prime 30 Y=1 40 Y=nxtprm(Y) 50 C=C+1:print 
               C;Y;"-"; 60 D=str(C):Z=str(Y) 70 E=len(D):F=len(Z) 80 for Q=2 to 
               E 90 A=mid(D,Q,1):G=val(A) 100 I=I+G:print I; 110 next Q 120 for 
               R=2 to F 130 B=mid(Z,R,1):H=val(B) 140 J=J+H:print J; 150 next R 
               160 if I=prmdiv(I) and J=prmdiv(J) and I=J then stop 170 I=0:J=0 
               180 goto 40
%Y A117477 Cf. A117478, A033548-A033549, A117458-A117463.
%Y A117477 Sequence in context: A142616 A132249 A033548 this_sequence A089316 A142129 
               A068680
%Y A117477 Adjacent sequences: A117474 A117475 A117476 this_sequence A117478 A117479 
               A117480
%K A117477 easy,nonn,base
%O A117477 1,1
%A A117477 Enoch Haga (Enokh(AT)comcast.net), Mar 19 2006

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