%I
%S 4,12,16,18,20,32,36,40,52,54,56,60,68,72,84,88,90,92,96,104,108,112,
%T 128,132,140,144,150,156,160,162,164,180,184,192,196,198,200,204,212,
%U 216,220,228,232,234,236,240,248,250,252,256,264,268,270,272,284,292,294,300,304,306,308,312
%N Squareful numbers with both neighbors squarefree.
%C Subsequence of A013929 and A067874.
%e 4 is in this sequence because 4 = 2^2 is nonsquarefree and both 4  1 = 3 and 4 + 1 = 5 are squarefree.
%o (MAGMA) [n: n in [2..300]  not IsSquarefree(n) and IsSquarefree(n1) and IsSquarefree(n+1)];
%o (PARI) isok(n) = !issquarefree(n) && issquarefree(n1) && issquarefree(n+1); \\ _Michel Marcus_, Jun 18 2017
%Y Cf. A013929, A067874, A228649, A272799, A281192.
%K nonn,easy
%O 1,1
%A _JuriStepan Gerasimov_, Jan 16 2017
%E Definition corrected by _Jon E. Schoenfield_, Jun 18 2017
