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Search: id:A104214
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| A104214 |
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Numbers n such that the sum of the digits of the n-th lower twin prime is prime. |
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+0
1
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| 1, 2, 3, 5, 6, 9, 11, 13, 14, 15, 16, 18, 19, 20, 24, 27, 29, 31, 32, 33, 35, 36, 37, 40, 43, 45, 48, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 69, 71, 74, 76, 77, 80, 82, 84, 85, 86, 87, 88, 91, 94, 97, 98, 99, 101, 103, 104, 106, 109, 111, 112, 115, 116, 117, 118, 121
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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The 5-th lower twin prime is 29. 2+9=11 a prime, so 5 is listed.
The 4-th lower twin prime is 17. 1+7=8 so 4 is missing from the table.
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PROGRAM
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(PARI) sdtwprime(n) = { local(x, y); for(x=1, n, y=sumdigits(twinl(x)); if(isprime(y), print1(x", ") ) ) } sumdigits(n) = \ The sum of the digits of n { local(x, j, s=0); x=digits(n); for(j=1, length(x), s+=x[j]; ); return(s) } digits(n) = \ The vector of the digits of n { return(eval(Vec(Str(n)))) }
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CROSSREFS
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Sequence in context: A026461 A026168 A113238 this_sequence A046657 A102825 A070991
Adjacent sequences: A104211 A104212 A104213 this_sequence A104215 A104216 A104217
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KEYWORD
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easy,nonn,base
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Mar 13 2005
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