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A152247 a(1) = 1. a(2) = 3. a(n) is the smallest odd positive integer not yet occurring in the sequence such that gcd(a(n), a(n-1)) > 1. 1
1, 3, 9, 15, 5, 25, 35, 7, 21, 27, 33, 11, 55, 45, 39, 13, 65, 75, 51, 17, 85, 95, 19, 57, 63, 49, 77, 91, 105, 69, 23, 115, 125, 135, 81, 87, 29, 145, 155, 31, 93, 99, 111, 37, 185, 165, 117, 123, 41, 205, 175, 119, 133, 147, 129, 43, 215, 195, 141, 47, 235, 225, 153 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

From Matthew Vandermast, Nov 21 2009: (Start)

Odd analog of the EKG sequence. Cf. A064413.

In contrast to A064413, there are at least 2 different patterns by which primes > a(2) are introduced into the sequence. 5 is the first of many primes p that are immediately preceded in the sequence by 3p and immediately followed by 5p. For p = 7, 19, or 31, p is immediately preceded by 5p and immediately followed by 3p. (End)

LINKS

Table of n, a(n) for n=1..63.

CROSSREFS

Cf. A152248.

Sequence in context: A175351 A050005 A272026 * A253765 A077932 A272458

Adjacent sequences:  A152244 A152245 A152246 * A152248 A152249 A152250

KEYWORD

nonn

AUTHOR

Leroy Quet, Nov 30 2008

EXTENSIONS

Extended by Ray Chandler, Dec 05 2008

STATUS

approved

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Last modified August 18 13:25 EDT 2019. Contains 326100 sequences. (Running on oeis4.)