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Search: id:A162252
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| A162252 |
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Numbers of the form prime(prime(prime(k))) with a digit sum which is prime. |
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+0
1
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| 5, 11, 179, 331, 599, 919, 1297, 1523, 1787, 2221, 3259, 3637, 3943, 4397, 5381, 6113, 6661, 6823, 8221, 9859, 10631, 11953, 12097, 12301, 12547, 12763, 13469, 14723, 15641, 15823, 17627, 18149, 19577, 20063, 20773, 21529, 23431, 26371, 26489
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Members of A038580 with a digit sum which is prime.
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FORMULA
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{A038508(k): A007953(A038508(k)) in A000040, any k}.
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EXAMPLE
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For k=6, prime(prime(prime(6))) = A038580(6)=179. The digit sum 1+7+9 = 17 is prime, so 179 is in the sequence.
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MAPLE
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read("transforms") ; A038580 := proc(n) ithprime(ithprime(ithprime(n))) ; end:
for n from 1 to 80 do if isprime(digsum(A038580(n))) then printf("%d, ", A038580(n)) ; fi; od: # R. J. Mathar, Aug 14 2009
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PROGRAM
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(PARI) sodip2(n, m) = /* m multiple nesting of prime(prime(prime..(n) */
{ local(s=0, a, x, y, j, p);
for(x=1, n, p=prime(x);
for(i=1, m, p=prime(p));
a=eval(Vec(Str(p))); y=sum(j=1, length(a), a[j]); if(isprime(y), print1(p", ")); )
}
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CROSSREFS
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Sequence in context: A083418 A020453 A036932 this_sequence A006572 A159009 A139187
Adjacent sequences: A162249 A162250 A162251 this_sequence A162253 A162254 A162255
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KEYWORD
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nonn,base
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AUTHOR
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Cino Hilliard (hillcino368(AT)hotmail.com), Jun 28 2009
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EXTENSIONS
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Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 14 2009
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