login
A087238
First differences of A057809.
1
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
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
KEYWORD
nonn
AUTHOR
Labos Elemer, Sep 04 2003
STATUS
approved