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
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 25 2009
STATUS
approved