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A328817
Numbers k such that at least 7 of k, k+1, ..., k+9 are divisible by their least prime factor squared.
1
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
1,1
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10000 (first 600 terms from Harvey P. Dale)
EXAMPLE
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.
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 *)
PROG
(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
CROSSREFS
Cf. A283050.
Sequence in context: A253365 A109484 A232889 * A159215 A176380 A156773
KEYWORD
nonn
AUTHOR
Sean A. Irvine (on behalf of Donald S. McDonald), Nov 07 2019
STATUS
approved