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A075544
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Primes which are the sum of the digital root of the first n primes for some n.
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2
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2, 5, 17, 19, 23, 31, 37, 43, 71, 163, 179, 199, 263, 269, 347, 379, 389, 443, 467, 487, 499, 569, 601, 641, 643, 647, 683, 691, 709, 769, 821, 829, 857, 859, 919, 941, 947, 953, 967, 997, 1019, 1021, 1061, 1093, 1123, 1153, 1231, 1249, 1381, 1409, 1459
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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s = 0; Do[s = s + Mod[ Prime[n], 9]; If[ PrimeQ[s], Print[s]], {n, 1, 350} ]
Select[Accumulate[Mod[Prime[Range[1000]], 9]], PrimeQ] (* Harvey P. Dale, May 04 2012 *)
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PROG
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(PARI) sumdigits2(n)=local(c); while (n>9, c=0; while (n>0, c=c+n%10; n=n-n%10; n=n/10); n=c); n
c=0; forprime (p=2, 1000, c=c+sumdigits2(p); if (isprime(c), print1(c, ", ")))
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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