A038493 Sums of 3 distinct powers of 12.

157, 1741, 1873, 1884, 20749, 20881, 20892, 22465, 22476, 22608, 248845, 248977, 248988, 250561, 250572, 250704, 269569, 269580, 269712, 271296, 2985997, 2986129, 2986140, 2987713, 2987724, 2987856, 3006721, 3006732, 3006864, 3008448, 3234817, 3234828, 3234960

Offset: 1

Author

Olivier Gérard

Keywords

• nonn
• easy

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Base-12 interpretation of A038445.

Cf. A001021, A038492.

Programs

Mathematica

Union[Total/@Subsets[12^Range[0,6],{3}]] (* Harvey P. Dale, Sep 06 2012 *)

Python

from math import isqrt, comb
from sympy import integer_nthroot
def A038493(n): return 12**((r:=n-1-comb((m:=integer_nthroot(6*n,3)[0])+(t:=(n>comb(m+2,3)))+1,3))-comb((k:=isqrt(b:=r+1<<1))+(b>k*(k+1)),2))+12**((a:=isqrt(s:=n-comb(m-(t^1)+2,3)<<1))+((s<<2)>(a<<2)*(a+1)+1))+12**(m+t+1) # Chai Wah Wu, Apr 04 2025

Extensions

Offset corrected by Amiram Eldar, Jul 14 2022