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A126616 a(n) = n for n < 10, a(10*n) = a(n), and if the terms a(10), a(20), a(30), ... are deleted, one gets back the original sequence. 8

%I

%S 1,2,3,4,5,6,7,8,9,1,1,1,1,1,1,1,1,1,1,2,1,2,1,2,1,2,1,2,1,3,2,1,3,2,

%T 1,3,2,1,3,4,2,1,3,4,2,1,3,4,2,5,1,3,4,2,5,1,3,4,2,6,5,1,3,4,2,6,5,1,

%U 3,7,4,2,6,5,1,3,7,4,2,8,6,5,1,3,7,4,2,8,6,9,5,1,3,7,4,2,8,6,9,1,5,1,3,7,4

%N a(n) = n for n < 10, a(10*n) = a(n), and if the terms a(10), a(20), a(30), ... are deleted, one gets back the original sequence.

%C A self-generating sequence.

%C Invented by Eric Angelini. Might also be called a lizard sequence (une suite du lézard) because it grows back from its tail.

%D J.-P. Delahaye, La suite du lézard et autres inventions, Pour la Science, No. 353, 2007.

%p A126616 := proc(n) option remember ; if n < 10 then n ; elif n mod 10 = 0 then A126616(n/10) ; else A126616( n-floor(n/10) ) ; fi ; end: seq(A126616(n),n=1..120) ; # _R. J. Mathar_, Oct 02 2007

%o (PARI) a(n,m=10)=while(n>=m,if(n%m,n-=n\m,n\=m));n \\ _M. F. Hasler_, Mar 07 2015

%Y Cf. A117943, A178931, A255824 - A255829.

%K nonn,easy

%O 1,2

%A _N. J. A. Sloane_, Feb 09 2007

%E More terms from _R. J. Mathar_, Oct 02 2007

%E Definition rephrased by _M. F. Hasler_, Mar 09 2015

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Last modified February 17 02:33 EST 2019. Contains 320200 sequences. (Running on oeis4.)