%I #20 Feb 20 2022 23:05:32

%S 1,111,120,121,123,131,132,133,134,141,142,144,145,151,152,155,156,

%T 161,162,166,167,171,172,177,178,181,182,188,189,191,192,199,219,221,

%U 231,232,234,242,243,244,245,252,253,255,256,262,263,266,267,272,273,277

%N a(n) is the smallest number larger than a(n-1) that has only three digits in common with a(n-1).

%C Terms computed by _Claudio Meller_.

%e a(10) = 141 because it is the smallest number greater than a(9) = 134 that has exactly three digits in common.

%e Similarly, a(33) = 219 because it is the smallest number greater than a(32) = 199 that has exactly three digits in common (the digit 9 of 219 is in common with the first and second 9 of 199).

%o (Python)

%o from itertools import islice

%o def c(s, t): return sum(t.count(si) for si in s)

%o def agen(): # generator of terms

%o an, target = 1, "1"

%o while True:

%o yield an

%o k = an + 1

%o while c(str(k), target) != 3: k += 1

%o an, target = k, str(k)

%o print(list(islice(agen(), 52))) # _Michael S. Branicky_, Jan 30 2022

%o (PARI) isok(k, d, va) = {if (#select(x->(x==k), va), return(0)); my(dk=digits(k)); sum(i=1, #dk, #select(x->(x==dk[i]), d)) == 3;}

%o lista(nn) = {my(va = vector(nn)); va[1] = 1; for (n=2, nn, my(k=va[n-1], d = digits(va[n-1])); while(!isok(k,d,va), k++); va[n] = k;); va;} \\ _Michel Marcus_, Jan 31 2022

%Y Cf. A350444, A350445, A350671, A350672, A351059.

%K nonn,base

%O 1,2

%A _Rodolfo Kurchan_, Jan 30 2022