%I A008463
%S A008463 9,81,65,61,37,58,89,145,42,20,4,16,37,58,89,145,42,20,4,16,37,
%T A008463 58,89,145,42,20,4,16,37,58,89,145,42,20,4,16,37,58,89,145,
%U A008463 42,20,4,16,37,58,89,145,42,20,4,16,37,58,89,145,42,20,4,16,37,58,89,145,
               42,20,4,16,37,58,89,145
%N A008463 Take sum of squares of digits of previous term.
%D A008463 R. Honsberger, Ingenuity in Math., Random House, 1970, p. 83.
%D A008463 A. Porges, A set of eight numbers, Amer. Math. Monthly, 52 (1945), 379-382.
%F A008463 Periodic with period 8.
%F A008463 a(n)=A000218(n+1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 
               24 2008
%F A008463 a(n)=A080709(n-2) for n>4. [From M. F. Hasler (MHasler(AT)univ-ag.fr), 
               May 24 2009]
%o A008463 Contribution from M. F. Hasler (MHasler(AT)univ-ag.fr), May 24 2009: 
               (Start)
%o A008463 (PARI) /* The given terms have been checked as follows: */
%o A008463 a=[/* paste the terms here */]; k=3; vector(#a,n,k=A003132(k))==a
%o A008463 /* PARI code: */ A008463(n)=[9,81,65,61,37, 58,89,145,42,20,4,16][if(n>
               12,(n-5)%8+5,n)]
%o A008463 /* This code has been checked as follows: */ k=3;vector(99,n,k=A003132(k))==vector(99,
               n,A008463(n)) \\\\ (End)
%Y A008463 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), A008462 
               (starting with 8), A008463 (starting with 9), A139566 (starting with 
               15), A122065 (starting with 74169). [From M. F. Hasler (MHasler(AT)univ-ag.fr), 
               May 24 2009]
%Y A008463 Sequence in context: A117817 A107346 A014393 this_sequence A043087 A037414 
               A161147
%Y A008463 Adjacent sequences: A008460 A008461 A008462 this_sequence A008464 A008465 
               A008466
%K A008463 nonn,base
%O A008463 1,1
%A A008463 N. J. A. Sloane (njas(AT)research.att.com).