login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A333480
Lexicographically earliest sequence of distinct positive integers such that the decimal expansions of neither a(n)/a(n+1) nor a(n+1)/a(n) contains a significant digit present in either a(n) or a(n+1).
1
2, 3, 5, 6, 8, 4, 11, 40, 12, 400, 22, 24, 72, 44, 36, 9, 18, 48, 16, 80, 33, 37, 45, 15, 50, 30, 20, 60, 54, 66, 55, 82, 75, 25, 220, 32, 288, 96, 396, 88, 64, 192, 576, 640, 480, 144, 4000, 110, 41, 148, 74, 90, 27, 81, 165, 495, 297, 99, 198, 540, 150, 444, 364, 2002, 224, 42, 7, 14, 70, 21
OFFSET
1,1
COMMENTS
By "significant digit" we mean to exclude from the quotients any zeros preceding the first nonzero digit, as well as zeros following the last nonzero digit (as in a terminating decimal).
Is the sequence infinite?
EXAMPLE
a(1)/a(2) = 2/3 = 0.666... and a(2)/a(1) = 3/2 = 1.5 and their combined distinct significant digits (1,5,6) are exclusive of the combined distinct digits of a(1) and a(2), (2,3).
a(7)/a(8) = 11/40 = 0.275 and a(8)/a(7) = 40/11 = 3.636363... and their combined distinct significant digits (2,3,5,6,7) are exclusive of the combined distinct digits of a(7) and a(8), (0,1,4).
a(106)/a(107) = 624/208 = 3 and a(107)/a(106) = 208/624 = 0.333... and their combined distinct significant digits (3) is exclusive of the combined distinct digits of a(106) and a(107), (0,2,4,6,8).
CROSSREFS
Sequence in context: A357132 A067183 A269670 * A373600 A377738 A036587
KEYWORD
nonn,base
AUTHOR
Eric Angelini and Hans Havermann, Mar 23 2020
STATUS
approved