A032754
Palindromic Super-6 Numbers.
Original entry on oeis.org
2023202, 374929473, 458353854, 499202994, 749858947, 3461771643, 8094884908, 10282628201, 11564046511, 11721612711, 12427872421, 12548784521, 12968986921, 18649794681, 19775857791, 19953035991, 22113331122
Offset: 1
- C. A. Pickover, "Keys to Infinity", New York: Wiley, p. 7, 1995.
A102832
Number of n-digit squares which contain the string "666" but not "6666".
Original entry on oeis.org
0, 0, 0, 0, 0, 0, 3, 21, 78, 302, 1139, 4156, 14791, 52529, 183565, 635691, 2183533, 7314869, 25303217
Offset: 1
-
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 *)
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