A138610 Nonsquarefree numbers congruent to 3 mod 4.

27, 63, 75, 99, 135, 147, 171, 175, 207, 243, 275, 279, 315, 343, 351, 363, 375, 387, 423, 459, 475, 495, 507, 531, 539, 567, 575, 603, 639, 675, 711, 735, 747, 775, 783, 819, 847, 855, 867, 875, 891, 927, 931, 963, 975, 999, 1035, 1071, 1075, 1083, 1107

Offset

1,1

Comments

Or, terms in A004767 but not in A039957.

The asymptotic density of this sequence is 1/4 - 2/Pi^2 = 0.047357... (A190357) - Amiram Eldar, Feb 10 2021

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Formula

A013929 INTERSECT A004767.

Maple

remove(numtheory:-issqrfree, [seq(i, i=3..1200, 4)]); # Robert Israel, Dec 18 2019

Mathematica

<<NumberTheory`NumberTheoryFunctions` Select[Range[3, 2000, 4], SquareFreeQ[ # ]==False&]
Select[Range[3, 1200, 4], !SquareFreeQ[#]&] (* Harvey P. Dale, Aug 27 2024 *)

Prog

(Magma) [4*n+3: n in [0..280] | not IsSquarefree(4*n+3)];  // Bruno Berselli, Mar 04 2011

Crossrefs

Cf. A004767, A013929, A039957, A190357.

Sequence in context: A157500 A180574 A107580 * A128530 A373763 A044129

Adjacent sequences: A138607 A138608 A138609 * A138611 A138612 A138613

Keyword

nonn

Author

Zak Seidov, May 14 2008

Status

approved