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 A272342 #19 Jun 29 2023 11:26:13 %S A272342 27,216,1728,13824,110592,884736,7077888,56623104,452984832, %T A272342 3623878656,28991029248,231928233984,1855425871872,14843406974976, %U A272342 118747255799808,949978046398464,7599824371187712,60798594969501696 %N A272342 a(n) = 27*8^n. %C A272342 a(n) are cubes that can be expressed as sum of exactly four distinct powers of two: a(n)=2^3n + 2^(3n+1) + 2^(3n+3) + 2^(3n+4). For example a(0) = 2^0 + 2^1 + 2^3 + 2^4 = 1 + 2 + 8 + 16 = 27. It is conjectured the a(n) are the only cubes that can be expressed as sum of exactly four distinct nonnegative powers of two (tested on cubes up to (10^7)^3). %H A272342 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (8). %F A272342 a(n) = 27*8^n = 2^3n + 2^(3n+1) + 2^(3n+3) + 2^(3n+4). %F A272342 a(n) = 8*a(n-1), n>0; a(0)=27. %F A272342 G.f.: 27/(1-8*x). %F A272342 E.g.f.: 27*exp(8*x). %F A272342 a(n) = 27*A001018(n). - _Michel Marcus_, Apr 26 2016 %t A272342 nmax=120; 27*8^Range[0, nmax] %o A272342 (PARI) a(n) = 27*8^n; \\ _Michel Marcus_, Apr 27 2016 %Y A272342 Cf. A001018, A002063. %K A272342 nonn,easy %O A272342 0,1 %A A272342 _Andres Cicuttin_, Apr 26 2016