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A102832 Number of n-digit squares which contain the string "666" but not "6666". 0
0, 0, 0, 0, 0, 0, 3, 21, 78, 302, 1139, 4156, 14791, 52529, 183565, 635691, 2183533, 7314869, 25303217 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

LINKS

Table of n, a(n) for n=1..19.

MATHEMATICA

fQ[n_] := StringPosition[ ToString[n^2], "666"] != {} && StringPosition[ ToString[n^2], "6666"] == {}; t = Table[0, {20}]; Do[ If[ fQ[n], t[[ Ceiling[ Log[10, n^2]] + 1]]++ ], {n, 3162277661}]; t (* Robert G. Wilson v, Mar 10 2005 *)

t6[digs_]:=Module[{a=Floor[Sqrt[10^(digs-1)]], b=Floor[ Sqrt[ 10^digs]]}, Count[ Range[a, b]^2, _?(SequenceCount[IntegerDigits[#], {6, 6, 6}]> 0&&SequenceCount[IntegerDigits[#], {6, 6, 6, 6}]==0&)]]; Table[ t6[n], {n, 20}] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 26 2021 *)

CROSSREFS

Cf. A052041, A075415, A102807 A032746.

Sequence in context: A067002 A110450 A176646 * A112851 A253943 A034490

Adjacent sequences:  A102829 A102830 A102831 * A102833 A102834 A102835

KEYWORD

nonn,base

AUTHOR

James R. Buddenhagen, Feb 27 2005

EXTENSIONS

a(13)-a(19) from Robert G. Wilson v, Mar 03 2005

STATUS

approved

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Last modified November 29 21:32 EST 2021. Contains 349416 sequences. (Running on oeis4.)