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A100714 Number of runs in binary expansion of A000040(n) (the n-th prime number) for n>0. 6
2, 1, 3, 1, 3, 3, 3, 3, 3, 3, 1, 5, 5, 5, 3, 5, 3, 3, 3, 3, 5, 3, 5, 5, 3, 5, 3, 5, 5, 3, 1, 3, 5, 5, 7, 5, 5, 5, 5, 7, 5, 7, 3, 3, 5, 3, 5, 3, 3, 5, 5, 3, 3, 3, 3, 3, 5, 3, 7, 5, 5, 7, 5, 5, 5, 5, 7, 7, 7, 7, 5, 5, 5, 7, 5, 3, 5, 5, 5, 5, 5, 7, 5, 5, 5, 5, 3, 5, 5, 3, 5, 3, 3, 5, 3, 3, 3, 5, 5, 5, 5, 7, 5, 5, 5 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

a(n)=A005811(A000040(n))

Record values of a(n)=2, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, ... are set at the indices n=1, 3, 12, 35, 121, 355, 1317, 4551, 15897, 56475, 197249, 737926, ... - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 02 2007

LINKS

Eric Weisstein's World of Mathematics, "Run-Length Encoding."

EXAMPLE

a(5)=3 because A000040(5)=11_10=1011_2, which splits into three runs ({1}, {0}, {1,1})

MATHEMATICA

Table[Length[Split[IntegerDigits[Prime[n], 2]]], {n, 1, 128}]

CROSSREFS

Cf. A005811, A000040.

Sequence in context: A003139 A145652 A111248 * A050123 A081386 A143802

Adjacent sequences:  A100711 A100712 A100713 * A100715 A100716 A100717

KEYWORD

base,easy,nonn

AUTHOR

Joseph Biberstine (jrbibers(AT)indiana.edu), Dec 11 2004

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Last modified February 15 15:20 EST 2012. Contains 205823 sequences.