A161183 Terms which occur at least twice in A161182.

1, 9, 16, 25, 53, 78, 82, 89, 115, 120, 130, 152, 161, 178, 196, 224, 233, 235, 250, 256, 265, 286, 291, 300, 301, 314, 315, 325, 347, 357, 360, 368, 381, 391, 397, 419, 428, 430, 456, 468, 479, 483, 484, 494, 495, 512, 528, 570, 577, 589, 591, 608, 610, 620

Offset

1,2

Comments

A161182 is not monotonic, so some terms (like 89) listed here are not direct neighbors in A161182. - R. J. Mathar, Jun 22 2009

Links

Table of n, a(n) for n=1..54.

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: L := [] ; for n from 1 to 1200 do L := [op(L), A161182(n)] ; od: read("transforms3") ; L := sort(L) ; L := LISTDUPL(L, 0) ; # R. J. Mathar, Jun 22 2009

Mathematica

f[n_] := 2n - 1 - PrimePi[n^2] + PrimePi[(n-1)^2];
Select[Split[Array[f, 1000]//Sort], Length[#] >= 2&][[All, 1]]
(* Jean-François Alcover, Mar 07 2023 *)

Crossrefs

Cf. A078435, A161182.

Sequence in context: A092941 A075393 A336449 * A183345 A303873 A257496

Adjacent sequences: A161180 A161181 A161182 * A161184 A161185 A161186

Keyword

easy,nonn

Author

Daniel Tisdale, Jun 05 2009

Extensions

Edited by N. J. A. Sloane, Jun 07 2009

Missing numbers added by R. J. Mathar, Jun 22 2009

Status

approved