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 A008462 #38 Sep 08 2022 08:44:35
%S A008462 8,64,52,29,85,89,145,42,20,4,16,37,58,89,145,42,20,4,16,37,58,89,145,
%T A008462 42,20,4,16,37,58,89,145,42,20,4,16,37,58,89,145,42,20,4,16,37,58,89,
%U A008462 145,42,20,4,16,37,58,89,145,42,20,4,16,37,58,89,145,42,20,4,16,37,58,89,145
%N A008462 Take sum of squares of digits of previous term; start with 8.
%D A008462 R. Honsberger, Ingenuity in Math., Random House, 1970, p. 83.
%H A008462 Vincenzo Librandi, <a href="/A008462/b008462.txt">Table of n, a(n) for n = 1..100</a>
%H A008462 Arthur Porges, <a href="http://www.jstor.org/stable/2304639">A set of eight numbers</a>, Amer. Math. Monthly 52 (1945), 379-382.
%H A008462 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 1).
%F A008462 Periodic with period 8.
%F A008462 a(n) = A080709(n-1) for n >= 5 and a(n) = A000221(n-1) = A008460(n+4) for all n >= 4. - _M. F. Hasler_, May 24 2009; edited and extended Apr 27 2018
%F A008462 From _Colin Barker_, Apr 28 2018: (Start)
%F A008462 G.f.: x*(8 + 64*x + 52*x^2 + 29*x^3 + 85*x^4 + 89*x^5 + 145*x^6 + 42*x^7 + 12*x^8 - 60*x^9 - 36*x^10 + 8*x^11 - 27*x^12) / ((1 - x)*(1 + x)*(1 + x^2)*(1 + x^4)).
%F A008462 a(n) = a(n-8) for n>13.
%F A008462 (End)
%t A008462 NestList[Total[IntegerDigits[#]^2]&, 8, 80] (* _Vincenzo Librandi_, Jan 29 2013 *)
%t A008462 PadRight[{8,64,52,29,85},80,{20,4,16,37,58,89,145,42}] (* _Harvey P. Dale_, Dec 27 2019 *)
%o A008462 (PARI) A008462(n)=[8, 64, 52, 29, 85, 89, 145, 42, 20, 4, 16, 37, 58][if(n>13,(n-6)%8+6,n)] \\ _M. F. Hasler_, May 24 2009
%o A008462 (Magma) [8, 64, 52, 29, 85] cat &cat[[89, 145, 42, 20, 4, 16, 37, 58]: n in [0..17]]; // _Vincenzo Librandi_, Jan 29 2013
%o A008462 (PARI) Vec(x*(8 + 64*x + 52*x^2 + 29*x^3 + 85*x^4 + 89*x^5 + 145*x^6 + 42*x^7 + 12*x^8 - 60*x^9 - 36*x^10 + 8*x^11 - 27*x^12) / ((1 - x)*(1 + x)*(1 + x^2)*(1 + x^4)) + O(x^60)) \\ _Colin Barker_, Apr 28 2018
%Y A008462 Cf. A003132 (the iterated map), A003621, A039943, A099645, A031176, A007770, A000216 (starting with 2), A000218 (starting with 3), A080709 (starting with 4), A000221 (starting with 5), A008460 (starting with 6), A008463 (starting with 9), A139566 (starting with 15), A122065 (starting with 74169). - _M. F. Hasler_, May 24 2009
%K A008462 nonn,base,easy
%O A008462 1,1
%A A008462 _N. J. A. Sloane_