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A242313 Numbers belonging to a geometric sequence whose ratio is 2 and whose first term ends in 1. 0
1, 2, 4, 8, 11, 16, 21, 22, 31, 32, 41, 42, 44, 51, 61, 62, 64, 71, 81, 82, 84, 88, 91, 101, 102, 111, 121, 122, 124, 128, 131, 141, 142, 151, 161, 162, 164, 168, 171, 176, 181, 182, 191, 201, 202, 204, 211, 221, 222, 231, 241, 242, 244, 248, 251, 256, 261 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Numbers such that A099551(n) = 1.
Numbers of the form 2^m * (10n + 1). - Charles R Greathouse IV, May 14 2014
LINKS
FORMULA
a(n) = 5n + O(log n). - Charles R Greathouse IV, May 14 2014
EXAMPLE
176 is in the sequence because it belongs to 11, 22, 44, 88, 176, with first term 11.
96, which belongs to 3, 6, 12, 24, 48, 96 with first term 3, is not a term.
PROG
(PARI) isok(n) = ((n/2^valuation(n, 2)) % 10) == 1; \\ Michel Marcus, May 14 2014
CROSSREFS
Cf. A099551.
Sequence in context: A320448 A115797 A336627 * A003596 A018600 A018408
KEYWORD
nonn,base,easy
AUTHOR
J. Lowell, May 10 2014
EXTENSIONS
More terms from Michel Marcus, May 14 2014
STATUS
approved

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Last modified March 18 22:47 EDT 2024. Contains 370951 sequences. (Running on oeis4.)