A046269 -id:A046269 - cp's OEIS frontend

A046261 Largest palindromic substring in 3^n.

1, 3, 9, 7, 8, 4, 9, 8, 656, 9, 9, 1771, 1441, 323, 969, 434, 7, 9, 9, 162261, 44, 353, 313, 414, 282, 88, 828, 484, 767, 3773, 94649, 767, 888, 5665, 6996, 999, 999, 909, 2992, 76267, 545, 717, 989, 707, 232, 55, 959, 8778, 6336, 32923, 7897987, 3693963, 989

Offset: 0

Patrick De Geest, Jun 15 1998

Harvey P. Dale, Table of n, a(n) for n = 0..500

Cf. A046269.

Max/@Table[Select[FromDigits/@Flatten[Table[Partition[ IntegerDigits[ 3^k], n,1],{n,IntegerLength[3^k]}],1],PalindromeQ],{k,0,60}] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 25 2018 *)

A050724 Numbers k such that the decimal expansion of 3^k contains no pair of consecutive equal digits (probably finite).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 15, 16, 17, 18, 21, 22, 24, 26, 42, 66, 67, 133

Offset: 1

Patrick De Geest, Sep 15 1999

No additional terms up to 50000. - Harvey P. Dale, Nov 15 2011

No additional terms up to 100000. - Michel Marcus, Oct 16 2019

			3^133 = 2865014852390475710679572105323242035759805416923029389510561523.

Cf. A000244, A030700, A046261, A046269.

q:= n-> (s-> andmap(i-> s[i]<>s[i+1], [$1..length(s)-1]))(""||(3^n)):
select(q, [$0..200])[];  # Alois P. Heinz, Mar 07 2024

Select[Range[0,500],!MemberQ[Differences[IntegerDigits[3^#]],0]&] (* Harvey P. Dale, Nov 15 2011 *)

isok(n) = {my(d = digits(3^n), c = d[1]); for (i=2, #d, if (d[i] == c, return (0)); c = d[i];); return (1);} \\ Michel Marcus, Oct 16 2019

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A046261 Largest palindromic substring in 3^n.

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A050724 Numbers k such that the decimal expansion of 3^k contains no pair of consecutive equal digits (probably finite).

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