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A154561
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Primes resulting from (sum of digits of k) + (sum of digits of prime(k)) as k runs through the positive integers.
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1
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3, 5, 11, 7, 13, 17, 23, 13, 23, 23, 13, 17, 23, 29, 19, 17, 29, 23, 17, 19, 23, 29, 23, 19, 31, 23, 17, 19, 29, 31, 31, 23, 11, 19, 19, 17, 19, 23, 17, 17, 17, 23, 29, 31, 23, 29, 23, 13, 19, 19, 31, 23, 23, 17, 11, 31, 23, 13, 23, 29, 23, 29, 29, 19, 23, 31, 37, 29, 37, 17
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OFFSET
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1,1
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LINKS
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EXAMPLE
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k=1 yields a term: prime(1) = 2 and 1 + 2 = 3 is prime, so a(1)=3;
k=2 yields a term: prime(2) = 3 and 2 + 3 = 5 is prime, so a(2)=5;
k=3 does not yield a term: prime(3) = 5 and 3 + 5 = 8 is composite;
k=4 yields a term: prime(4) = 7 and 4 + 7 = 11 is prime, so a(3)=11;
k=5 yields a term: prime(5) = 11 and 5 + 1 + 1 = 7 is prime, so a(4)=7.
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MAPLE
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A007953 := proc(n) add(d, d=convert(n, base, 10)) ; end proc:
for n from 1 to 300 do a := A007953(n) +A007953(ithprime(n)) ; if isprime(a) then printf("%d, ", a ) ; end if; end do: # R. J. Mathar, May 05 2010
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MATHEMATICA
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sod[n_]:=Total[IntegerDigits[n]]; Select[Table[sod[n]+sod[Prime[n]], {n, 300}], PrimeQ] (* Harvey P. Dale, Dec 11 2012 *)
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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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