cp's OEIS Frontend

A380413 Terms appearing twice in A378086 (number of nonsquarefree numbers < prime(n)).

%I A380413 #5 Feb 07 2025 21:32:07
%S A380413 0,1,11,14,39,53,109,179,222,240,251,319,337,481,505,508,578,664,674,
%T A380413 738,818,835,877,905,933,1041,1069,1098,1325,1352,1392,1535,1539,1567,
%U A380413 1652,1663,1732,1817,1849,1960,2134,2148,2158,2220,2387,2428,2457,2622,2625
%N A380413 Terms appearing twice in A378086 (number of nonsquarefree numbers < prime(n)).
%F A380413 a(n) = A378086(A068361(n)) = A378086(A068361(n)+1).
%t A380413 y=Table[Length[Select[Range[Prime[n]],!SquareFreeQ[#]&]],{n,100}];
%t A380413 Select[Most[Union[y]],Count[y,#]==2&]
%Y A380413 A000040 lists the primes, differences A001223, seconds A036263.
%Y A380413 A005117 lists the squarefree numbers, differences A076259.
%Y A380413 A013929 lists the nonsquarefree numbers, differences A078147, seconds A376593.
%Y A380413 A061399 counts nonsquarefree integers between primes, see A068361, A061398, A068360, A377783, A378086.
%Y A380413 A070321 gives the greatest squarefree number up to n.
%Y A380413 A071403 counts squarefree numbers < prime(n), see A373198, A337030.
%Y A380413 A112925 gives the greatest squarefree number between primes, least A112926.
%Y A380413 Cf. A057627, A065890, A378032 (differences A378034), A378033 (differences A378036).
%Y A380413 Cf. A072284, A120327, A224363, A378040, A378082, A378084.
%K A380413 nonn
%O A380413 1,3
%A A380413 _Gus Wiseman_, Feb 06 2025