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Search: id:A089776
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| A089776 |
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If n mod 10 is 1, 3, 7, or 9, then a(n) = least prime of the form 1 followed by n^r; else a(n) = least prime of the form n^r followed by a 1. In both cases r must be > 1 and a(n) = 0 if no such prime exists. |
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1
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| 11, 41, 13, 41, 251, 61, 17, 641, 19, 101, 114641, 0, 113, 75295361, 151, 40961, 1289, 181, 1361, 4001, 11025506433613486607375777617584133309366191904729927960524981845743709132117581\ , 1368800680154120519681, 1907846434775996175406740561329, 241, 251, 6761, 127, 281, 1500246412961, 9001, 131
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OFFSET
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1,1
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COMMENT
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Subsidiary sequence: 3 more sequences can be obtained by replacing 1 by 3,7 and 9.
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FORMULA
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If n is divisible by 2 or 5, a(n) = A088622(n); otherwise a(n) = A088623(n). - David Wasserman (wasserma(AT)spawar.navy.mil), Oct 12 2005
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EXAMPLE
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a(12) = 0 because 1+10*12^r is always divisible by 11.
a(32) = 0 because 1+10*32^r is divisible by 3 if r is odd and by 11 if r is even.
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CROSSREFS
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Cf. A088622, A088623.
Sequence in context: A056124 A064768 A135719 this_sequence A073626 A065144 A089348
Adjacent sequences: A089773 A089774 A089775 this_sequence A089777 A089778 A089779
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KEYWORD
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base,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Nov 24 2003
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EXTENSIONS
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More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Oct 12 2005
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