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A114991
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Primes of the form 2^a * 3^b * 5^c + 1 for positive a, b, c.
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1
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31, 61, 151, 181, 241, 271, 541, 601, 751, 811, 1201, 1621, 1801, 2161, 2251, 3001, 4051, 4801, 4861, 6481, 7681, 8101, 8641, 9001, 9601, 9721, 11251, 14401, 15361, 19441, 21601, 21871, 22501, 23041, 24001, 32401, 33751, 36451, 37501, 43201, 54001, 57601, 58321
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OFFSET
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1,1
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COMMENTS
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Compare with A005109 "Class 1- (or Pierpont) primes: primes of the form 2^t*3^u + 1." One might call this new sequence "(2,3,5)-Pierpont) primes."
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
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FORMULA
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(For a,b,c>0, 2^a * 3^b * 5^c + 1 IFF prime}. (For a,b,c>0, 2^a * 3^b * 5^c + 1 IFF in A000040}.
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EXAMPLE
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a(1) = 31 = 2^1 * 3^1 * 5^1 + 1.
a(2) = 61 = 2^2 * 3^1 * 5^1 + 1.
a(3) = 151 = 2^1 * 3^1 * 5^2 + 1.
a(4) = 181 = 2^2 * 3^2 * 5^1 + 1.
Values include 30000001 = 2^7 * 3^1 * 5^7 + 1, 90000000001 = 2^9 * 3^2 * 5^9 + 1.
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CROSSREFS
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Cf. A000040, A005109, A030430.
Cf. A143207
Sequence in context: A132230 A136066 A282326 * A225874 A139892 A088464
Adjacent sequences: A114988 A114989 A114990 * A114992 A114993 A114994
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post, Feb 22 2006
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STATUS
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approved
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