A087238 First differences of A057809.

2, 2, 2, 19, 3, 3, 63, 4, 20, 210, 5, 5, 10, 5, 5, 648, 72, 12, 24, 6, 6, 6, 1925, 7, 7, 7, 7, 7, 5314, 16, 16, 16, 8, 8, 15054, 9, 765, 40240, 40, 30, 10, 30, 40, 10, 10, 10, 110477, 305655, 12, 144, 12, 12, 12, 12, 12, 12, 12, 204, 60, 12, 36, 12, 12, 12, 12, 823046, 13

Offset

2,1

Links

Giovanni Resta, Table of n, a(n) for n = 2..1161

Formula

a(n)=A057809(n+1)-A057809(n)

Example

Large differences arise between max term in a cluster and least one in the next cluster of A057809. While small entries obtained as differences inside a cluster.
E.g.:...,21,6467079011,198,22,110,132,22,242,66,17541629593,23,... shows by first differences the transition from the 21st cluster to 23rd solution-set over the 22nd-set with multiples of 22.
First cluster is empty, while 11th contains one term (see A038227).

Mathematica

Differences[Select[Range[2, 1500000], Divisible[#, PrimePi[#]]&]] (* Harvey P. Dale, Aug 13 2012 *)

Crossrefs

Cf. A038623-A038627, A057809, A087235-A087242.

Sequence in context: A349642 A064215 A358633 * A226935 A099640 A140283

Adjacent sequences: A087235 A087236 A087237 * A087239 A087240 A087241

Keyword

nonn

Author

Labos Elemer, Sep 04 2003

Status

approved