A261010 Write 5^n in base 3, add up the "digits".

1, 3, 5, 7, 7, 9, 9, 13, 15, 13, 13, 17, 19, 21, 21, 27, 25, 25, 25, 23, 27, 33, 31, 39, 35, 45, 37, 57, 45, 47, 45, 45, 53, 47, 55, 51, 57, 59, 67, 67, 69, 65, 67, 65, 71, 79, 71, 65, 67, 75, 65, 71, 73, 83, 69, 79, 81, 85, 79, 89, 87, 95, 89, 85, 97, 99, 93, 101, 107

Offset: 0

Author

N. J. A. Sloane, Aug 14 2015

Keywords

• nonn
• base

Links

• Chai Wah Wu, Table of n, a(n) for n = 0..10000
• Cernenoks J., Iraids J., Opmanis M., Opmanis R., Podnieks K., Integer complexity: experimental and analytical results II, arXiv:1409.0446 [math.NT] (September 2014)
• K. Podnieks, Digits of pi: limits to the seeming randomness, arXiv:1411.3911 [math.NT], 2014.

Crossrefs

Sum of digits of k^n in base b for various pairs (k,b): A001370 (2,10), A011754 (3,2), A261009 (2,3), A261010 (5,3).

Programs

Maple

S:=n->add(i,i in convert(5^n,base,3)); [seq(S(n),n=0..100)];

Python

def digits(n, b=10): # digits of n in base 2 <= b <= 62
    x, y = n, ''
    while x >= b:
        x, r = divmod(x,b)
        y += str(r) if r < 10 else (chr(r+87) if r < 36 else chr(r+29))
    y += str(x) if x < 10 else (chr(x+87) if x < 36 else chr(x+29))
    return y[::-1]
def A261010(n):
    return sum([int(d) for d in digits(5**n,3)]) # Chai Wah Wu, Aug 14 2015