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A151780
a(n) = 5^(wt(n) - 1) where wt(n) = A000120(n).
6
1, 1, 5, 1, 5, 5, 25, 1, 5, 5, 25, 5, 25, 25, 125, 1, 5, 5, 25, 5, 25, 25, 125, 5, 25, 25, 125, 25, 125, 125, 625, 1, 5, 5, 25, 5, 25, 25, 125, 5, 25, 25, 125, 25, 125, 125, 625, 5, 25, 25, 125, 25, 125, 125, 625, 25, 125, 125, 625, 125, 625, 625, 3125, 1, 5, 5, 25, 5, 25, 25, 125, 5
OFFSET
1,3
EXAMPLE
From Omar E. Pol, Jul 21 2009: (Start)
If written as a triangle:
1;
1,5;
1,5,5,25;
1,5,5,25,5,25,25,125;
1,5,5,25,5,25,25,125,5,25,25,125,25,125,125,625;
1,5,5,25,5,25,25,125,5,25,25,125,25,125,125,625,5,25,25,125,25,125,125,625,...
(End)
PROG
(Python 3.10+)
def A151780(n): return 5**(n.bit_count()-1) # Chai Wah Wu, Nov 15 2022
(PARI) a(n) = 5^(hammingweight(n)-1); \\ Michel Marcus, Nov 15 2022
CROSSREFS
Essentially A151779/6.
Cf. A000351. - Omar E. Pol, Jul 21 2009
Sequence in context: A198366 A162797 A087232 * A054244 A093562 A081774
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 25 2009
STATUS
approved