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A135946
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Number of primes with 3n digits made of adjacent primes with 3 digits.
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2
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OFFSET
| 1,1
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COMMENTS
| Number of primes of the form: ... ddd3ddd2ddd1ddd0 = ddd0 * 10 ^ 0 + ddd1 * 10 ^ 3 + ddd2 * 10 ^ 6 + ddd3 * 10 ^ 9... where ddd0, ddd1, ddd2, ddd3... are prime with 3 digits. The i-th element of the sequence is the number of primes with i * 3 digits. Aproximation for the sum of the sequence up to a(k) for large values of k: sum( a(i), i =1 .. k ) = 10 ^ ( 3*k ) / ( ( 3*k )*log(10))* ( 143/1000)^(k-1).
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EXAMPLE
| Example: a(2) = 2753 because there are 2753 numbers of the form ddd1ddd0 with ddd0, ddd1 prime numbers i.e: 101107,101113,101149,101173,101197,101281,101293 ... 997991
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CROSSREFS
| Cf. A135944 A135945 A135946.
Sequence in context: A035304 A185514 A159054 * A199039 A199235 A029555
Adjacent sequences: A135943 A135944 A135945 * A135947 A135948 A135949
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KEYWORD
| nonn,base,bref
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AUTHOR
| Giorgio Balzarotti & Paolo P. Lava (greenblue(AT)tiscali.it), Dec 07 2007
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EXTENSIONS
| a(4) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Apr 17 2010
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