A388056 The decimal expansion of the n-th term of A007500, when read backwards, corresponds to that of the a(n)-th term of A007500.

1, 2, 3, 4, 5, 8, 10, 6, 11, 7, 9, 13, 12, 14, 35, 26, 17, 51, 19, 41, 43, 54, 23, 24, 56, 16, 27, 38, 40, 30, 52, 32, 33, 55, 15, 47, 37, 28, 50, 29, 20, 42, 21, 53, 45, 46, 36, 48, 49, 39, 18, 31, 44, 22, 34, 25, 211, 71, 82, 135, 98, 241, 112, 206, 117, 212

Offset

1,2

Comments

This sequence is a self-inverse permutation of the positive integers.

Fixed points correspond to indices of terms of A002385 in A007500.

Links

Rémy Sigrist, Table of n, a(n) for n = 1..11297

Rémy Sigrist, PARI program

Index entries for sequences that are permutations of the natural numbers

Formula

a(a(n)) = n.

A004086(A007500(n)) = A007500(a(n)).

Example

For n = 67: A007500(67) = 1151; its reversal, 1511, corresponds to A007500(93), so a(67) = 93.

Prog

(PARI) \\ See Links section.

Crossrefs

Cf. A002385, A004086, A007500, A095180, A388055 (binary variant).

Sequence in context: A085266 A280431 A056804 * A305399 A101547 A047597

Adjacent sequences: A388053 A388054 A388055 * A388057 A388058 A388059

Keyword

nonn,base

Author

Rémy Sigrist, Sep 14 2025

Status

approved