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Search: id:A088602
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| A088602 |
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Number of primes obtained by prefixing a single (nonzero) digit to 2n-1. |
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+0
1
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| 5, 6, 0, 5, 5, 4, 3, 0, 2, 4, 3, 3, 0, 4, 3, 4, 3, 0, 3, 5, 4, 3, 0, 4, 3, 3, 4, 0, 6, 3, 3, 5, 0, 4, 3, 3, 4, 0, 5, 3, 3, 5, 0, 4, 1, 4, 3, 0, 4, 3, 3, 1, 0, 3, 5, 4, 3, 0, 2, 5, 4, 3, 0, 3, 3, 4, 4, 0, 2, 5, 4, 3, 0, 4, 3, 3, 4, 0, 5, 3, 4, 5, 0, 3, 4, 3, 3, 0, 5, 2, 2, 5, 0, 5, 1, 4, 3, 0, 4, 2, 3, 2, 0, 3, 6
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OFFSET
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1,1
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COMMENT
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a(5k+3) = 0. The maximum value of a(n) is 6. If digits 1 to 9 are prefixed to 2n-1, exactly 3 numbers == 0 (mod 3). e.g. If (2n-10 == 0 (mod 3) then these are obtained on prefixing 3, 6 and 9. If (2n-1) == 1 (mod 3) then these are obtained on prefixing 2, 5 and 8. If (2n-1) == 2 (mod 3) then these are obtained on prefixing 1, 4 and 7.
Subsidiary sequences: (i) Start of the first occurrence of n successive zeros in this sequence. In the following subsequences the occurrence of a zero in between is to be neglected. (As a(3) onwards every fifth term is zero.) (ii) Start of the first occurrence of n successive ones in this sequence. etc. up to 6. (iii) Index of occurrence of 6. (iv)Index of occurrence of 5. etc.
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EXAMPLE
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a(10) = 4, 19 = 2*10-1, the four primes are 419, 619, 719, 919.
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CROSSREFS
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Sequence in context: A100220 A011440 A092161 this_sequence A021869 A103492 A105580
Adjacent sequences: A088599 A088600 A088601 this_sequence A088603 A088604 A088605
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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), Oct 15 2003
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EXTENSIONS
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More terms from Anne M. Donovan (anned3005(AT)aol.com) Nov 05 2003
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