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A052034
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Primes such that the sum of the squares of their digits is also a prime.
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10
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11, 23, 41, 61, 83, 101, 113, 131, 137, 173, 179, 191, 197, 199, 223, 229, 311, 313, 317, 331, 337, 353, 373, 379, 397, 401, 409, 443, 449, 461, 463, 467, 601, 641, 643, 647, 661, 683, 719, 733, 739, 773, 797, 829, 863, 883, 911, 919, 937, 971, 977, 991, 997, 1013
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Primes p such that the sum of the squared digits of p is a prime q. For the values of q see A109181.
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REFERENCES
| Charles W. Trigg, Journal of Recreational Mathematics, Vol. 20(2), 1988.
"Hands On Numbers Count", Personal Computer World, 1997, p. 290.
Clifford A. Pickover, A Passion for Mathematics, John Wiley & Sons, Inc., 2005, p. 89.
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EXAMPLE
| E.g. p=23 is OK because q=2^2+3^2=13 is a prime.
E.g. 9431 -> 9^2+4^2+3^2+1^2 = 107 and prime.
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MAPLE
| a:=proc(n) local nn, L: nn:=convert(n, base, 10): L:=nops(nn): if isprime(n)= true and isprime(add(nn[j]^2, j=1..L))=true then n else end if end proc: seq(a(n), n=1..1000); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 08 2008
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MATHEMATICA
| Select[Prime[Range[250]], PrimeQ[Total[IntegerDigits[#]^2]]&] [From Harvey P. Dale, Dec. 19, 2010]
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CROSSREFS
| Cf. A052035, A003132, A108662, A109181.
Sequence in context: A094376 A086524 A060915 * A077041 A190797 A068842
Adjacent sequences: A052031 A052032 A052033 * A052035 A052036 A052037
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KEYWORD
| nonn,base
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com), Dec 15 1999.
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EXTENSIONS
| Edited by N. J. A. Sloane (njas(AT)research.att.com), Dec 15 2007 and again on Dec 05 2008 at the suggestion of Zak Seidov
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