A328817 Numbers k such that at least 7 of k, k+1, ..., k+9 are divisible by their least prime factor squared.

3475, 18271, 25524, 25623, 45616, 55772, 72471, 72472, 104419, 121667, 133223, 133224, 149220, 164975, 165568, 165571, 172916, 180167, 180168, 203979, 203980, 219123, 260424, 261472, 261475, 334516, 334519, 364216, 381267, 393320, 393323, 402723, 412524, 420467, 420468

Offset: 1

Author

Sean A. Irvine (on behalf of Donald S. McDonald), Nov 07 2019

Keywords

• nonn

Examples

			203980 is a member since 2^2 | 203980, 37^2 | 203981, 13^2 | 203983, 2^2 | 203984, 3^2 | 203985, 7^2 | 203987, and 2^2 | 203988.
		

Links

• David A. Corneth, Table of n, a(n) for n = 1..10000 (first 600 terms from Harvey P. Dale)

Crossrefs

Cf. A283050.

Programs

Mathematica

Flatten[Position[Partition[Table[If[Divisible[n,FactorInteger[n][[1,1]]^2],1,0],{n,420000}],10,1],?(Total[#]>6&)]] (* _Harvey P. Dale, Jan 02 2021 *)

PARI

upto(n) = {my(l, c, res); l = List([0,0,0,1,0,0,0,1,1,0]); c = 3; res = List(); for(i = 11, n, f = factor(i)[,2]; c -= l[1]; listpop(l, 1); if(f[1] >= 2, c++; listput(l, 1) , listput(l, 0) ); if(c >= 7, listput(res, i-9); ) ); res } \\ David A. Corneth, Jan 02 2021