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A180133 Smallest k such that k*6^n is a sum of two successive primes. 9
5, 2, 1, 1, 4, 12, 2, 1, 4, 3, 5, 8, 7, 34, 8, 11, 33, 26, 13, 9, 13, 90, 15, 40, 30, 5, 43, 9, 69, 38, 27, 79, 47, 9, 36, 6, 1, 92, 44, 51, 50, 16, 81, 21, 9, 50, 84, 14, 45, 59, 124, 215, 36, 6, 1, 20, 31, 35, 33, 46, 18, 3, 23, 114, 19, 41, 84, 14, 8, 35, 114, 19, 73, 14, 39, 68, 42 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

If a(n) == 0 (mod 6), then a(n+1) = a(n)/6.

Records: 5, 12, 34, 90, 92, 124, 215, 249, 592, 601, 1099, 1282, 1406, 1589, 1700, 2688, ..., .

Corresponding primes which are twin primes for n = 0, 1, 2, 3, 4, 7, 13, 15, 28, 69, 120, 162, 251, 257, 279 ..., .

LINKS

Robert G. Wilson v, Table of n, a(n) for n = 0..500

MATHEMATICA

f[n_] := Block[{k = 1, j = 6^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, A180132, A180134, A179975, A180135, A180136, A180137, A180138.

Sequence in context: A104714 A085119 A010128 * A197419 A029764 A136301

Adjacent sequences:  A180130 A180131 A180132 * A180134 A180135 A180136

KEYWORD

base,nonn

AUTHOR

Zak Seidov & Robert G. Wilson v, Aug 15 2010

STATUS

approved

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Last modified November 21 17:20 EST 2017. Contains 295004 sequences.