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A124877
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Numbers n such that A007408(n) is prime.
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3
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3, 15, 19, 26, 31, 129, 139, 211, 242, 246, 251, 474, 552, 558, 694, 801, 1001, 1123, 1313, 1687, 4168, 4484, 5611, 6869
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| a(1) = 3 since A007408(3)= 251 is the first prime number of sequence A007408,
a(2) = 15 since A007408(15) = 56154295334575853 is the second prime number of sequence A007408.
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MAPLE
| select(isprime@A007408, [$1..200]);
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PROG
| (PARI) num=1; den=1; for(k=2, 2000, k3=k^3; s=(num*k3+den)/(den*k3); num=numerator(s); den=denominator(s); if(isprime(num), print1(k", "))) - Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 26 2008
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CROSSREFS
| Cf. A007408.
Cf. A125503. [From Alexander Adamchuk (alex(AT)kolmogorov.com), Apr 26 2010]
Sequence in context: A206367 A039570 A032644 * A111517 A083545 A097571
Adjacent sequences: A124874 A124875 A124876 * A124878 A124879 A124880
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KEYWORD
| hard,more,nonn
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AUTHOR
| M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 11 2006
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EXTENSIONS
| More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 26 2008
a(21)-a(24) from Alexander Adamchuk (alex(AT)kolmogorov.com), Apr 26 2010
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