%I #16 May 28 2023 10:49:23
%S 42,63,94,135,96,157,138,129,130,41,52,73,104,55,106,77,148,139,140,
%T 51,62,83,114,65,116,87,158,149,150,61,72,93,124,75,126,97,168,159,
%U 160,71,82,103,44,85,136,107,88,169,170,81,92,113,54,95,146,117,98,179,180,91,102,33,64,105,66,127,108,99,190,101,22,43,74,115,76,137,118,109,110,21,32,53,84,125,86,147,128,119,120,31,42,63
%N a(1) = 42; a(n) = 10*(sum of digits of a(n-1)) + (last digit of a(n-1)) + 1 for n >= 2.
%C The sequence is periodic: a(91) = a(1). - _Georg Fischer_, Jan 15 2021
%D Clifford A. Pickover, A Passion for Mathematics, John Wiley & Sons, Inc., 2005, pp. 103 and 311 (for "Trains with crystal balls").
%H <a href="/index/Rec#order_90">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).
%t nxt[n_]:=Module[{idn=IntegerDigits[n]},10Total[idn]+Last[idn]+1]; NestList[nxt,42,120] (* _Harvey P. Dale_, Jul 23 2011 *)
%Y Cf. A007953, A010879.
%K nonn,base,easy
%O 1,1
%A _Harvey P. Dale_, Jul 23 2011