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A137728
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Second digit from the end of product of first n primes.
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1
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0, 0, 3, 1, 1, 3, 1, 9, 7, 3, 3, 1, 1, 3, 1, 3, 7, 7, 9, 9, 7, 3, 9, 1, 7, 7, 1, 7, 3, 9, 3, 3, 1, 9, 1, 1, 7, 1, 7, 1, 9, 9, 9, 7, 9, 1, 1, 3, 1, 9, 7, 3, 3, 3, 1, 3, 7, 7, 9, 9, 7, 1, 7, 7, 1, 7, 7, 9, 3, 7, 1, 9, 3, 9, 1, 3, 7, 9, 9, 1, 9, 9, 9, 7, 3, 9, 1, 7, 7, 1, 7, 3, 1, 1, 9, 7, 3, 3, 9, 9, 3, 1, 3, 7, 7
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| a(1) = a(2) = 0 because Prime(1) = 2 and Prime(1)*Prime(2) = 6 are one-digit numbers.
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FORMULA
| a(n) = Mod[ p#/10, 10 ] for n>2 and a(1) = a(2) = 0.
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MATHEMATICA
| a(1) = a(2) = 0, for n>2 Table[ Mod[ Product[ Prime[n], {n, 1, k} ], 100 ]/10, {k, 3, 1000} ]
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CROSSREFS
| Cf. A007652 = Final digit of prime(n). Cf. A110923 = Final two digits of prime(n) (with leading zero omitted). Cf. A137727 = Final digit of prime(n)*prime(n+1). Cf. A002110 = Primorial numbers (first definition): product of first n primes. Sometimes written p#.
Sequence in context: A131327 A122506 A010274 * A054398 A093415 A106749
Adjacent sequences: A137725 A137726 A137727 * A137729 A137730 A137731
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KEYWORD
| nonn,base
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 08 2008
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