A073780 Number of 1's in base 3 representation of n-th prime.

0, 1, 1, 1, 1, 3, 1, 1, 1, 1, 3, 3, 3, 3, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 3, 3, 3, 3, 1, 3, 3, 3, 3, 1, 1, 1, 1, 1, 1, 3, 1, 3, 3, 1, 1, 3, 1, 1, 1, 1, 3, 1, 1, 3, 3, 3, 5, 3, 3, 3, 3, 1, 3, 5, 3, 3, 3, 3, 5, 5, 3, 3, 3, 3, 3, 3, 3, 3, 1, 3, 3, 3, 3, 3

Offset: 1

Author

Zak Seidov Aug 11 2002

Keywords

• base
• easy
• nonn

Examples

			a1(11)=3 as 11th prime, 31, is 1011 in base 3 representation.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A073779, A073781.

Programs

Mathematica

a1[n_] := Length[Cases[IntegerDigits[Prime[n], 3], 1]]
Table[DigitCount[n,3,1],{n,Prime[Range[100]]}] (* Harvey P. Dale, Feb 23 2015 *)

Formula

a(n) = A062756(A000040(n)). - Michel Marcus, Oct 02 2013