A218468 -id:A218468 - cp's OEIS frontend

A226179 Fixed points of A218468 (= least unused number which is a multiple of a digit of the preceding term).

1, 2, 10, 19, 20, 34, 51, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187

Offset: 1

M. F. Hasler, May 30 2013

Indices k for which A218468(k)=k, where A218468(k) is the least unused number to be a multiple of one digit of the preceding term of that sequence.

Hans Havermann first stated that 2*10^k is such a fixed point, for all k >= 0. More subsequences have been given by Lars Blomberg, see link.

Hans Havermann, Table of a218468(n) = n
L. Blomberg, H. Havermann et al., in reply to E. Angelini's OP, Re: a(n+1) is the multiple of at least one digit of a(n), SeqFan list, May 29 2013.

Cf. A218468.

A278649 Lexicographically earliest sequence of distinct terms such that, for any n>0, a(n+1) has a digit that divides a(n) and a(n) has a digit that divides a(n+1).

Original entry on oeis.org

1, 10, 2, 12, 3, 15, 5, 25, 14, 7, 21, 11, 13, 16, 4, 20, 18, 6, 24, 8, 32, 22, 26, 28, 34, 27, 30, 33, 36, 9, 63, 39, 51, 17, 19, 31, 41, 61, 71, 81, 23, 100, 29, 102, 35, 45, 50, 55, 65, 54, 52, 40, 44, 48, 56, 42, 38, 72, 46, 92, 62, 82, 104, 43, 105, 37

Offset: 1

Rémy Sigrist, Nov 25 2016

This sequence combines the constraints met in A218468 and in A257277.

Rémy Sigrist, Table of n, a(n) for n = 1..10000
Rémy Sigrist, PARI program for A278649

Cf. A218468, A257277.

a = {1}; Do[k = 2; While[Or[Nand[AnyTrue[#2, Divisible[a[[n - 1]], #] &],
AnyTrue[#1, Divisible[k, #] &]], MemberQ[a, k]] & @@ Map[DeleteCases[ IntegerDigits@ #, 0] &, {a[[n - 1]], k}], k++]; AppendTo[a, k], {n, 2, 66}]; a (* Michael De Vlieger, Nov 25 2016, Version 10 *)

cp's OEIS Frontend

A226179 Fixed points of A218468 (= least unused number which is a multiple of a digit of the preceding term).

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