A038481 - OEIS

%I #11 Feb 09 2018 03:22:53

%S 8,50,56,344,350,392,2402,2408,2450,2744,16808,16814,16856,17150,

%T 19208,117650,117656,117698,117992,120050,134456,823544,823550,823592,

%U 823886,825944,840350,941192,5764802,5764808,5764850,5765144,5767202

%N Sums of 2 distinct powers of 7.

%H Robert Israel, <a href="/A038481/b038481.txt">Table of n, a(n) for n = 0..10010</a>

%F G.f.: ((1-x)*(1-7*x))^(-1) * (2 - 8*x + sum_{k>=0} ((1+5*7^k)*x^(k*(k+1)/2) + (1+41*7^k)*x^(1+k*(k+1)/2))). - _Robert Israel_, Feb 09 2018

%p seq(seq(7^i+7^j,j=0..i-1),i=1..10); # _Robert Israel_, Feb 09 2018

%t Sort[Total/@Subsets[7^Range[0,10],{2}]] (* _Harvey P. Dale_, Jul 29 2015 *)

%Y Base 7 interpretation of A038444.

%K nonn,easy

%O 0,1

%A _Olivier Gérard_