A338841 - OEIS

A338841

No odd digit is present in a(n) * a(n+1).

0, 1, 2, 3, 8, 5, 4, 6, 7, 12, 17, 24, 10, 20, 11, 22, 13, 16, 14, 19, 32, 9, 52, 39, 58, 36, 18, 26, 31, 28, 15, 40, 21, 42, 53, 54, 46, 44, 47, 60, 34, 59, 38, 69, 94, 30, 68, 33, 62, 43, 48, 50, 56, 73, 88, 23, 96, 25, 80, 35, 64, 41, 104, 27, 84, 51, 122, 71, 66, 37, 72, 29, 76, 79, 112, 74, 63, 102, 61

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OFFSET

1,3

COMMENTS

This is the lexicographically earliest sequence of distinct nonnegative terms with this property and also a permutation of the nonnegative integers.

LINKS

Carole Dubois, Table of n, a(n) for n = 1..5000

Index entries for sequences that are permutations of the nonnegative integers

EXAMPLE

a(1) * a(2) = 0 * 1 = 0 (no odd digit is present);

a(2) * a(3) = 1 * 2 = 2 (no odd digit is present);

a(3) * a(4) = 2 * 3 = 6 (no odd digit is present);

a(4) * a(5) = 3 * 8 = 24 (no odd digit is present); etc.

MATHEMATICA

Block[{a = {0}}, Do[Block[{k = 1}, While[Nand[FreeQ[a, k], NoneTrue[IntegerDigits@ Total[a[[-1]]*k], OddQ]], k++]; AppendTo[a, k]], {i, 2, 79}]; a] (* Michael De Vlieger, Nov 12 2020 *)

CROSSREFS

Cf. A014263 (no odd digits).

Cf. A338839, A338840, A338842, A338843, A338844, A338845, A338846 (variants on the same idea).

Sequence in context: A244915 A244668 A192646 * A100208 A277972 A222243

Adjacent sequences: A338838 A338839 A338840 * A338842 A338843 A338844

KEYWORD

nonn,base,look

AUTHOR

Eric Angelini and Carole Dubois, Nov 11 2020

STATUS

approved