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A073215 Sum of two powers of 23.

%I A073215 #35 Apr 09 2025 15:13:42
%S A073215 2,24,46,530,552,1058,12168,12190,12696,24334,279842,279864,280370,
%T A073215 292008,559682,6436344,6436366,6436872,6448510,6716184,12872686,
%U A073215 148035890,148035912,148036418,148048056,148315730,154472232,296071778
%N A073215 Sum of two powers of 23.
%H A073215 G. C. Greubel, <a href="/A073215/b073215.txt">Table of n, a(n) for n = 0..999</a> [Offset changed to 0 by _Georg Fischer_, Mar 01 2022]
%F A073215 T(n, m) = 23^n + 23^m, for n >= 0 and m in [0..n].
%F A073215 Bivariate g.f.: (2 - 24*x) / ((1 - x) * (1 - 23*x) * (1 - 23*x*y)). - _J. Douglas Morrison_, Jul 29 2021
%e A073215 T(2,0) = 23^2 + 23^0 = 530.
%e A073215 Table begins:
%e A073215        2;
%e A073215       24,     46;
%e A073215      530,    552,   1058;
%e A073215    12168,  12190,  12696,  24334;
%e A073215   279842, 279864, 280370, 292008, 559682;
%e A073215   ...
%t A073215 With[{nn=30},Take[Union[Total/@Tuples[23^Range[0,nn],2]],nn]] (* _Harvey P. Dale_, Oct 16 2017 *)
%o A073215 (Python)
%o A073215 from math import isqrt
%o A073215 def A073215(n): return 23**(a:=(k:=isqrt(m:=n<<1))+(m>k*(k+1))-1)+23**(n-1-(a*(a+1)>>1)) # _Chai Wah Wu_, Apr 09 2025
%Y A073215 Cf. A009967.
%Y A073215 Equals twice A072822.
%Y A073215 Sums of two powers of n: A073423 (0), A007395 (1), A173786 (2), A055235 (3), A055236 (4), A055237 (5), A055257 (6), A055258 (7), A055259 (8), A055260 (9), A052216 (10), A073211 (11), A194887 (12), A072390 (13), A055261 (16), A073213 (17), A073214 (19).
%K A073215 easy,nonn,tabl
%O A073215 0,1
%A A073215 _Jeremy Gardiner_, Jul 20 2002