%I A108564
%S A108564 0,1,1,2,4,8,15,29,56,18,118,122,134,239,136,136,456,679,147,1148,234,
%T A108564 228,1577,1378,1347,345,4467,3577,3679,1268,11299,12389,23568,24458,
%U A108564 11477,12789,22279,137,24668,35789,23788,23488,13377,24469,12258,23579
%N A108564 a(0) = 0, a(1) = 1, a(2) = 1, a(3) = 2, a(4) = 4, for n>3: a(n+1) = SORT[a(n) 
               + a(n-1) + a(n-2) + a(n-3)], where SORT places digits in ascending 
               order and deletes 0's.
%C A108564 Sorted tetranacci numbers, a.k.a. sorted Fibonacci 4-step sequence.
%C A108564 As found by T. D. Noe (noe(AT)sspectra.com): Max=4556699. Cycle period=41652. 
               Cycle starts with the 23944th term.
%D A108564 Richard I. Hess, "Problem 920: sorted Fibonacci sequence", Pi Mu Epsilon 
               Journal, Vol. 10 (Fall 1998) No. 9, pp. 754-755.
%e A108564 a(8) = SORT[a(4) + a(5) + a(6) + a(7)] = SORT[108] = 18.
%e A108564 a(10) = SORT[a(6) + a(7) + a(8) + a(9)] = SORT[221] = 122.
%Y A108564 Cf. A000078, A069638, A107281, 108565-108573.
%Y A108564 Sequence in context: A088532 A036621 A001383 this_sequence A066369 A000078 
               A034338
%Y A108564 Adjacent sequences: A108561 A108562 A108563 this_sequence A108565 A108566 
               A108567
%K A108564 base,easy,nonn
%O A108564 0,4
%A A108564 Jonathan Vos Post (jvospost3(AT)gmail.com), Jun 10 2005