A352341 - OEIS

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A352341

Numbers whose maximal Pell representation (A352339) is palindromic.

0, 1, 3, 6, 8, 10, 20, 27, 40, 49, 54, 58, 63, 68, 88, 93, 119, 136, 150, 167, 221, 238, 288, 300, 310, 322, 334, 338, 360, 372, 382, 394, 406, 508, 530, 542, 696, 737, 771, 812, 833, 867, 908, 942, 983, 1242, 1276, 1317, 1392, 1681, 1710, 1734, 1763, 1792, 1802

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OFFSET

1,3

COMMENTS

A000129(n) - 2 is a term for n > 1. The maximal Pell representations of these numbers are 0, 11, 121, 1221, 12221, ... (0 and A132583).

A048739 is a subsequence since these are the repunit numbers in the maximal Pell representation.

A065113 is a subsequence since the maximal Pell representation of A065113(n) is 2*n 2's.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

The first 10 terms are:

n a(n) A352339(a(n))

-- ---- -------------

1 0 0

2 1 1

3 3 11

4 6 22

5 8 111

6 10 121

7 20 1111

8 27 1221

9 40 2222

10 49 11111

MATHEMATICA

pell[1] = 1; pell[2] = 2; pell[n_] := pell[n] = 2*pell[n - 1] + pell[n - 2]; pellp[n_] := Module[{s = {}, m = n, k}, While[m > 0, k = 1; While[pell[k] <= m, k++]; k--; AppendTo[s, k]; m -= pell[k]; k = 1]; IntegerDigits[Total[3^(s - 1)], 3]]; lazy[n_] := Module[{v = pellp[n]}, nv = Length[v]; i = 1; While[i <= nv - 2, If[v[[i]] > 0 && v[[i + 1]] == 0 && v[[i + 2]] < 2, v[[i ;; i + 2]] += {-1, 2, 1}; If[i > 2, i -= 3]]; i++]; i = Position[v, _?(# > 0 &)]; If[i == {}, 0, FromDigits[v[[i[[1, 1]] ;; -1]]]]]; Select[Range[0, 2000], PalindromeQ[lazy[#]] &]

CROSSREFS

Cf. A000129, A048739, A065113, A132583, A352339.

Similar sequences: A002113, A006995, A014190, A094202, A331191, A351712, A351717, A352087, A352105, A352319.

Sequence in context: A228707 A290218 A310135 * A124051 A294086 A350159

Adjacent sequences: A352338 A352339 A352340 * A352342 A352343 A352344

KEYWORD

nonn,base

AUTHOR

Amiram Eldar, Mar 12 2022

STATUS

approved