A090593 Smallest prime with exactly n consecutive ones in the longest run of ones in its binary expansion.

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

Links

Chai Wah Wu, Table of n, a(n) for n = 1..3310

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

Cf. A090000, A090587.

Sequence in context: A058181 A198959 A000231 * A030090 A260298 A283807

Adjacent sequences: A090590 A090591 A090592 * A090594 A090595 A090596

Keyword

nonn,base

Author

Robert G. Wilson v, Dec 03 2003

Extensions

a(28)-a(32) from Donovan Johnson, Sep 10 2013

Status

approved