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A075538 a(1)=1, a(2)=2, then use "merge and minus": a(n)=merge(a(1),...,a(n-1))-a(1)-...-a(n-1)). 1

%I

%S 1,2,9,117,128988,129116999871,129117128987999999870883,

%T 129117128988129116999870999999999999870882871012,

%U 129117128988129116999871129117128987999999870882999999999999999999999999870882871011870883000129

%N a(1)=1, a(2)=2, then use "merge and minus": a(n)=merge(a(1),...,a(n-1))-a(1)-...-a(n-1)).

%C A rapidly growing sequence.

%F a(1)=1, a(2)=2, a(n)=merge(a(1), ..., a(n-1))-a(1)-...-a(n-1).

%e a(3)=9 because a(1)=1,a(2)=2 and a(3)=merge(a(1),a(2))-a(1)-a(2)=12-1-2=9; then a(4)=117 because a(4)=merge(a(1),a(2),a(3))-a(1)-a(2)-a(3)=129-1-2-9=117.

%t se={1, 2}; a=1; b=2; me=ToString[a]<>ToString[b]; su=a+b; Do[ab=ToExpression[me]-su; se=Append[se, ab]; su=su+ab; me=ToString[me]<>ToString[ab], {i, 10}]; se

%Y Cf. A075537.

%K nonn

%O 1,2

%A _Zak Seidov_, Sep 20 2002

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Last modified May 31 08:09 EDT 2020. Contains 334747 sequences. (Running on oeis4.)