A161182 Successive differences between positions of squares in list of nonprimes.

1, 1, 3, 5, 6, 9, 9, 12, 13, 16, 16, 19, 20, 22, 25, 25, 26, 30, 31, 33, 34, 36, 38, 41, 40, 43, 46, 47, 48, 51, 53, 53, 56, 57, 60, 61, 64, 66, 65, 68, 69, 72, 76, 75, 78, 78, 83, 82, 82, 89, 90, 88, 89, 95, 96, 100, 101, 98, 104, 103, 105, 110, 108, 112, 115, 115, 118, 120

Offset: 1

Author

Daniel Tisdale, Jun 05 2009

Keywords

• nonn

Links

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

Crossrefs

Cf. A078435, sequence of positions of squares in sequence of nonprimes.

Programs

Maple

A038107 := proc(n) numtheory[pi]( n^2) ; end: A078435 := proc(n) n^2-A038107(n) ; end: A161182 := proc(n) A078435(n)-A078435(n-1) ; end: seq(A161182(n),n=1..100) ; # R. J. Mathar, Jun 22 2009

Mathematica

With[{nn=5000},Differences[Flatten[Position[Complement[Range[0,nn], Prime[ Range[ PrimePi[nn]]]],?(IntegerQ[Sqrt[#]]&)]]]] (* _Harvey P. Dale, Mar 03 2014 *)

Formula

a(n) = A078435(n) - A078435(n-1). - R. J. Mathar, Jun 22 2009

Extensions

Corrected and extended by R. J. Mathar, Jun 22 2009