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URL: https://oeis.org/A090593

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A090593
Smallest prime with exactly n consecutive ones in the longest run of ones in its binary expansion.
4
2, 3, 7, 47, 31, 191, 127, 1021, 3583, 4093, 6143, 16381, 8191, 81919, 262139, 1114111, 131071, 786431, 524287, 4194301, 14680063, 16777213, 67108859, 654311423, 671088637, 738197503, 536870909, 5368709117, 3758096383, 34359738337, 2147483647, 21474836479
OFFSET
1,1
EXAMPLE
a(1) = 2 since 2_d = 10_b. a(2) = 3 since 3_d = 11_b. a(3) = 7 since 7_d = 111_b. a(4) = 47 since 47_d = 101111_b.
MATHEMATICA
a = Table[0, {30}]; NextPrim[n_] := Block[{k = n + 1}, While[ ! PrimeQ[k], k++ ]; k]; p = 2; Do[ m = Length[ Union[ DeleteCases[ Split[ IntegerDigits[p, 2]], 0, 2]][[ -1]]]; If[ a[[m]] == 0, a[[m]] = p]; p = NextPrim[p], {n, 1, 117000000}]
CROSSREFS
Sequence in context: A058181 A198959 A000231 * A030090 A260298 A283807
KEYWORD
nonn,base
AUTHOR
Robert G. Wilson v, Dec 03 2003
EXTENSIONS
a(28)-a(32) from Donovan Johnson, Sep 10 2013
STATUS
approved