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A179532 a(n) = 2^ceiling(n*(n+1)/3). 1
1, 2, 4, 16, 128, 1024, 16384, 524288, 16777216, 1073741824, 137438953472, 17592186044416, 4503599627370496, 2305843009213693952, 1180591620717411303424, 1208925819614629174706176, 2475880078570760549798248448 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
Hankel transform of A128750. Satisfies (4,0) Somos-4 recurrence 4*a(n-1)*a(n-3)/a(n-4) = a(n),n>3.
LINKS
FORMULA
a(n) = a(-1-n) for all n in Z. - Michael Somos, Aug 14 2018
MATHEMATICA
Table[2^Ceiling[(n(n+1))/3], {n, 0, 20}] (* Harvey P. Dale, Sep 25 2013 *)
PROG
(PARI) vector(20, n, n--; 2^ceil(n*(n+1)/3)) \\ G. C. Greubel, Aug 14 2018
(Magma) [2^Ceiling((n(n+1))/3): n in [0..20]]; // G. C. Greubel, Aug 14 2018
CROSSREFS
Sequence in context: A334351 A009200 A144526 * A217994 A174677 A073924
KEYWORD
nonn
AUTHOR
Paul Barry, Jan 08 2011
STATUS
approved

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Last modified July 25 05:51 EDT 2024. Contains 374586 sequences. (Running on oeis4.)