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
Programs
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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
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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 *)
Extensions
Edited by N. J. A. Sloane, Jun 07 2009
Missing numbers added by R. J. Mathar, Jun 22 2009
Comments