A329764 a(1) = 1; thereafter a(n+1) > a(n) is the smallest multiple of a(n) using only odd digits but not divisible by 9.

1, 3, 15, 75, 375, 9375, 159375, 71559375, 1195399359375, 353915911333359375, 51915571117579153359375, 753315397517553377717399173359375, 3319771735775931191533111595353537393933359375

Offset

1,2

Comments

Equivalently, the sequence is defined as a(1) = 1, a(2) = 3, a(3) = 15, and for n > 2, a(n+1) > a(n) is the smallest multiple of a(n) using only odd digits. All terms besides a(1) and a(2) are divisible by 5.

Links

Table of n, a(n) for n=1..13.

Crossrefs

Cf. A329762, A078221, A078223.

Sequence in context: A002902 A236579 A005053 * A183411 A136778 A300665

Adjacent sequences: A329761 A329762 A329763 * A329765 A329766 A329767

Keyword

nonn,base

Author

Chai Wah Wu, Dec 04 2019

Status

approved