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 A180132 Smallest k such that k*5^n is a sum of two successive primes. 9
 5, 1, 4, 10, 2, 8, 12, 12, 36, 12, 28, 66, 30, 6, 18, 132, 36, 108, 34, 14, 48, 60, 12, 22, 150, 30, 6, 74, 54, 16, 8, 66, 150, 30, 6, 14, 374, 110, 22, 82, 62, 66, 108, 348, 114, 428, 190, 38, 570, 114, 102, 24, 82, 86, 178, 420, 84, 108, 328, 186, 126, 192, 76, 82, 24 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS If a(n) == 0 (mod 5), then a(n+1) = a(n)/5. Records: 5, 10, 12, 36, 66, 132, 150, 374, 428, 570, 734, 840, 1938, 2036, 2220, 2968, 3132, 3444, 4014, 6090, ..., . Corresponding primes which are twin primes for n = 0, 1, 51, 102, 103, 202, 275, ..., . LINKS Robert G. Wilson v, Table of n, a(n) for n = 0..500 MATHEMATICA f[n_] := Block[{k = 1, j = 5^n/2}, While[ h = k*j; PrimeQ@h || NextPrime[h, -1] + NextPrime@h != 2 h, k++ ]; k]; Array[f, 80, 0] CROSSREFS Cf. A180130, A180131, A180133, A180134, A179975, A180135, A180136, A180137, A180138. Sequence in context: A179290 A167864 A011301 * A105664 A094882 A019840 Adjacent sequences:  A180129 A180130 A180131 * A180133 A180134 A180135 KEYWORD base,nonn AUTHOR Zak Seidov & Robert G. Wilson v, Aug 15 2010 STATUS approved

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Last modified May 20 08:53 EDT 2013. Contains 225458 sequences.