A038479 Sums of 3 distinct powers of 6.
43, 223, 253, 258, 1303, 1333, 1338, 1513, 1518, 1548, 7783, 7813, 7818, 7993, 7998, 8028, 9073, 9078, 9108, 9288, 46663, 46693, 46698, 46873, 46878, 46908, 47953, 47958, 47988, 48168, 54433, 54438, 54468, 54648, 55728, 279943, 279973, 279978, 280153, 280158, 280188
Offset: 1
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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Maple
N:= 9: # to get all terms < 6^(N+1) seq(seq(seq(6^i+6^j+6^k,k=0..j-1),j=1..i-1),i=2..N);
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Mathematica
Union[Total/@Subsets[6^Range[0,8],{3}]] (* Harvey P. Dale, May 17 2011 *) -
Python
from math import isqrt, comb from sympy import integer_nthroot def A038479(n): return 6**((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))+6**((a:=isqrt(s:=n-comb(m-(t^1)+2,3)<<1))+((s<<2)>(a<<2)*(a+1)+1))+6**(m+t+1) # Chai Wah Wu, Apr 05 2025
Extensions
Offset changed by Robert Israel, May 08 2018
Comments