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Search: id:A154408
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| A154408 |
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Number p (prime) such that (p^2+1)/10 is prime |
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+0
2
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| 7, 13, 17, 23, 37, 53, 67, 97, 103, 113, 127, 137, 163, 167, 197, 223, 227, 263, 277, 283, 347, 367, 373, 383, 397, 433, 503, 547, 587, 617, 653, 673, 677, 683, 773, 797, 823, 877, 883, 937, 947, 953, 997, 1063, 1103, 1117, 1163, 1187, 1213, 1367, 1423, 1447
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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37 is in the sequence because both 37 and (37^2 + 1)/10 = 137 are primes. [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 21 2009]
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MAPLE
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a := proc (n) if isprime(n) = true and type((1/10)*n^2+1/10, integer) = true and isprime((1/10)*n^2+1/10) = true then n else end if end proc: seq(a(n), n = 2 .. 1700); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 21 2009]
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CROSSREFS
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Cf. A017305
Sequence in context: A108334 A136083 A167276 this_sequence A154411 A089531 A138337
Adjacent sequences: A154405 A154406 A154407 this_sequence A154409 A154410 A154411
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KEYWORD
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nonn
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AUTHOR
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Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 09 2009
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EXTENSIONS
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Corrected and extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 21 2009
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