%I #12 Sep 20 2024 03:04:47
%S 1,3,6,11,18,25,33,44,57,68,81,99,116,134,152,177,200,223,246,276,304,
%T 331,360,397,433,465,501,541,579,617,662,707,749,793,845,895,944,995,
%U 1051,1105,1161,1214,1279,1337,1397,1456,1528,1591,1657,1722,1799,1870
%N a(n) = position of 2*n^3 in A003325.
%H Robert Israel, <a href="/A024667/b024667.txt">Table of n, a(n) for n = 1..2000</a>
%F It appears that a(n) ~ 2^(2/3) * Pi^2 * n^2/(9 * Gamma(2/3)^3). - _Robert Israel_, Sep 19 2024
%p M:= 200: # to get a(1) .. a(M)
%p N:= 2*N^3:
%p A:=sort(convert({seq(seq(x^3 + y^3, y = 1 .. floor((N-x^3)^(1/3))),x=1..floor(N^(1/3)))},list)):
%p filter:= proc(n) local F;
%p if n::odd then return false fi;
%p F:= ifactors(n/2)[2][..,2] mod 3;
%p andmap(`=`,F,0)
%p end proc:
%p select(t -> filter(A[t]), [$1..nops(A)]); # _Robert Israel_, Sep 19 2024
%Y Cf. A003325.
%K nonn
%O 1,2
%A _Clark Kimberling_