A390002

Created: 10/27/2025 | Author: Vincenzo Manto , Oct 21 2025

Leading digit of 15^n.

Sequence Chart

Data

1,1,2,3,5,7,1,1,2,3,5,8,1,1,2,4,6,9,1,2,3,4,7,1,1,2,3,5,8,1,1,2,4,6,9,1,2,3,4,7,1,1,2,3,5,8,1,1,2,4,6,9,1,2,3,4,7,1,1,2,3,5,8,1,1,2,4,6,9,1,2,3,4,7,1,1,2,3,5,8,1,1,2,4,6,9,1

Formula

a(n) = A000030(A001024(n)).

a(n) = floor(10^frac(n*log_10(15))). - _Mia Boudreau_, Nov 02 2025

Computational Implementations

PYTHON

def a(n): return int(str(15**n)[0])
print([a(n) for n in range(50)])

CODE

a(n) = digits(15^n)[1]; \\ _Michel Marcus_, Oct 22 2025

CODE

int a(int n){return new BigInteger("15").pow(n).toString().charAt(0)-'0'; } // Mia Boudreau, Nov 02 2025

Mathematica

a[n_] := IntegerDigits[15^n][[1]]; Array[a, 100, 0]

A390002

Sequence Chart

Data

Formula

Computational Implementations

PYTHON

CODE

CODE

Mathematica

Cross-References