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 A345240 #24 Sep 26 2024 19:37:29
%S A345240 1,52,158,229,278,284,304,235,289,291,300,153,251,298,291,300,153,251,
%T A345240 298,291,300,153,251,298,291,300,153,251,298,291,300,153,251,298,291,
%U A345240 300,153,251,298,291,300,153,251,298,291,300,153,251,298,291,300,153,251,298
%N A345240 a(1) = 1; thereafter a(n) = A161406(a(n-1)).
%C A345240 A Spanish analog of A345126 (British English) and A345157 (US English).
%C A345240 Starting from n = 10 the sequence becomes periodic with period 5: repeat [291, 300, 153, 251, 298].
%H A345240 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,1).
%t A345240 a[1]=1;a[n_]:=a[n]=Total[If[#=="ñ",15,If[(s=LetterNumber@#)>14,s+1,s]]&/@Characters@StringDelete[IntegerName[a[n-1],"Spanish"],{" ","-"}]];Array[a,100] (* _Giorgos Kalogeropoulos_, Jun 11 2021 *)
%t A345240 PadRight[{1,52,158,229,278,284,304,235,289},120,{300,153,251,298,291}] (* _Harvey P. Dale_, Sep 26 2024 *)
%Y A345240 Cf. A073327, A161406, A169639, A344013, A345126, A345157.
%K A345240 nonn,word,easy
%O A345240 1,2
%A A345240 _Omar E. Pol_ and _N. J. A. Sloane_, Jun 11 2021