A081102 Numbers k such that the first k digits of log_10(2) after the decimal point are primes.

1, 64, 1126, 1653, 13680, 27453

Offset

1,2

Links

Table of n, a(n) for n=1..6.

Example

1 is listed because 3 is prime but 5 is not listed because 30102 is not prime.

Mathematica

Do[ If[ PrimeQ[ FromDigits[ RealDigits[ N[ Log[10, 2], n + 10], 10, n] [ [1] ] ] ], Print[n] ], {n, 1, 10000} ]

Crossrefs

Cf. A007524.

Sequence in context: A191494 A269000 A189276 * A250171 A128987 A240788

Adjacent sequences: A081099 A081100 A081101 * A081103 A081104 A081105

Keyword

nonn,base,more

Author

John Sillcox (JMS21187(AT)aol.com), Apr 15 2003

Extensions

Offset corrected and a(5)-a(6) added by Amiram Eldar, Jan 27 2021

Status

approved