A038480 -id:A038480 - cp's OEIS frontend

A038478 Sums of 2 distinct powers of 6.

7, 37, 42, 217, 222, 252, 1297, 1302, 1332, 1512, 7777, 7782, 7812, 7992, 9072, 46657, 46662, 46692, 46872, 47952, 54432, 279937, 279942, 279972, 280152, 281232, 287712, 326592, 1679617, 1679622, 1679652, 1679832, 1680912, 1687392, 1726272, 1959552, 10077697, 10077702

Offset: 1

Olivier Gérard

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

Base-6 interpretation of A038444.

Cf. A000400, A038479, A038480.

Total/@Subsets[6^Range[0,10],{2}]//Union (* Harvey P. Dale, Aug 11 2018 *)

from math import isqrt
def A038478(n): return 6**(m:=isqrt(n<<3)+1>>1)+6**(n-1-(m*(m-1)>>1)) # Chai Wah Wu, Apr 04 2025

Offset corrected by Amiram Eldar, Jul 14 2022

A038479 Sums of 3 distinct powers of 6.

Original entry on oeis.org

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

Olivier Gérard

Robert Israel, Table of n, a(n) for n = 1..10000

Base-6 interpretation of A038445.

Cf. A000400, A038478, A038480.

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);

Union[Total/@Subsets[6^Range[0,8],{3}]] (* Harvey P. Dale, May 17 2011 *)

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

Offset changed by Robert Israel, May 08 2018

cp's OEIS Frontend

A038478 Sums of 2 distinct powers of 6.

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