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 A008460 #31 Oct 21 2022 22:07:45 %S A008460 6,36,45,41,17,50,25,29,85,89,145,42,20,4,16,37,58,89,145,42,20,4,16, %T A008460 37,58,89,145,42,20,4,16,37,58,89,145,42,20,4,16,37,58,89,145,42,20,4, %U A008460 16,37,58,89,145,42,20,4,16,37,58,89,145,42,20,4,16,37,58,89,145,42,20,4 %N A008460 Take sum of squares of digits of previous term; start with 6. %D A008460 R. Honsberger, Ingenuity in Mathematics, Random House, 1970, p. 83. %H A008460 Vincenzo Librandi, <a href="/A008460/b008460.txt">Table of n, a(n) for n = 1..100</a> %H A008460 Arthur Porges, <a href="http://www.jstor.org/stable/2304639">A set of eight numbers</a>, Amer. Math. Monthly 52 (1945), 379-382. %H A008460 <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 A008460 Periodic with period 8. %F A008460 a(13+n) = A080709(n). - _M. F. Hasler_, May 24 2009 %t A008460 NestList[Total[IntegerDigits[#]^2]&, 6, 80] (* _Vincenzo Librandi_, Jan 29 2013 *) %o A008460 (PARI) A008460(n)=[6,36,45,41,17, 50,25,29,85,89, 145,42,20,4,16, 37,58][if(n<18,n,(n-10)%8+10)] \\ _M. F. Hasler_, May 24 2009 %o A008460 (Magma) [6, 36, 45, 41, 17, 50, 25, 29, 85] cat &cat[[89, 145, 42, 20, 4, 16, 37, 58]: n in [0..17]]; // _Vincenzo Librandi_, Jan 29 2013 %Y A008460 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), A008462 (starting with 8), A008463 (starting with 9), A139566 (starting with 15), A122065 (starting with 74169). - _M. F. Hasler_, May 24 2009 %K A008460 nonn,base,easy %O A008460 1,1 %A A008460 _N. J. A. Sloane_ %E A008460 An erroneous (duplicate) term deleted by _M. F. Hasler_, May 24 2009