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A329447
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Look left and tell the least frequent: after a(0) = 0, a(n) = 10c + d, where c > 0 is the number of times the least frequent digit d has appeared so far; smallest d in case of tie.
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5
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0, 10, 11, 20, 12, 22, 30, 13, 23, 33, 40, 14, 24, 34, 44, 50, 15, 25, 35, 45, 55, 60, 16, 26, 36, 46, 56, 66, 70, 17, 27, 37, 47, 57, 67, 77, 80, 18, 28, 38, 48, 58, 68, 78, 88, 90, 19, 29, 39, 49, 59, 69, 79, 89, 99, 100, 112, 113, 114, 115, 116, 117, 118, 119, 120, 123, 124, 125, 126, 127, 128, 129
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OFFSET
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0,2
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COMMENTS
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The terms "10c + d" are to be read "c digits d (have appeared so far)", as in the "look and see" sequences A045918 and similar.
An analog sequence may be computed for any other initial term a(0). Sequence A329448 lists the starting values that will appear a second time later in the respective sequence.
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LINKS
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MAPLE
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a[0]:= 0;
S[0]:= 1:
for i from 1 to 9 do S[i]:= 0 od:
for n from 1 to 100 do
a[n]:= min(select(`>=`, [seq(10*S[i]+i, i=0..9)], 10));
L:= convert(a[n], base, 10);
for d from 0 to 9 do S[d]:= S[d] + numboccur(d, L) od;
od:
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PROG
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(PARI) A329447_vec(N)={my(c=Vec(1, 10), t); vector(N, i, for(j=1, #i=vecsort(c, , 1), if(c[i[j]], i=i[j]; break)); for(j=1, #i=digits(t=c[i]*10+i-1), c[i[j]+1]++); t)} \\ Returns the vector a(1..N)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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