This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A170803 #8 Feb 05 2025 12:37:01 %S A170803 1,3,6,10,18,27,43,70,102,166,247,375,618,874,1386,2115,3139,5187, %T A170803 7374,11470,18031,26223,42607,62290,95058,154107,219643,350715,527862, %U A170803 790006,1314294,1845735,2894311,4488634,6585786,10780090,15563059,23951667,38300574 %N A170803 Partial sums of A006899. %H A170803 Reinhard Zumkeller, <a href="/A170803/b170803.txt">Table of n, a(n) for n = 1..1000</a> %o A170803 (Haskell) %o A170803 a170803 n = a170803_list !! (n-1) %o A170803 a170803_list = scanl1 (+) a006899_list -- _Reinhard Zumkeller_, Oct 09 2013 %o A170803 (Python) %o A170803 from sympy import integer_log %o A170803 def A170803(n): return ((a:=1<<k+1)<<1)-2+(3**integer_log(a,3)[0]*3-1>>1) if 6**(k:=integer_log(m:=3**(n-1),6)[0])<<1<m else ((a:=3**integer_log(1<<n,6)[0])*3-1>>1)+(1<<a.bit_length())-2 # _Chai Wah Wu_, Feb 05 2025 %Y A170803 Cf. A006899, A170804, A170805. %K A170803 nonn %O A170803 1,2 %A A170803 _N. J. A. Sloane_, Dec 12 2009