A375078 - OEIS

%I #30 Aug 04 2024 11:16:09

%S 1,0,0,0,0,0,0,0,0,8,1,0,0,0,0,0,0,1,0,15,4,0,0,1,1,0,0,1,0,20,7,1,0,

%T 1,1,0,1,1,0,24,12,3,1,2,1,0,1,1,0,26,17,5,1,2,2,1,2,1,0,27,21,10,1,2,

%U 2,1,3,1,0,29,26,14,2,3,2,2,3,1,1,29,29,19

%N a(1)=1; thereafter a(n) is the number of digits in (n mod 10) already present in the sequence.

%H Paolo P. Lava, <a href="/A375078/b375078.txt">Table of n, a(n) for n = 1..10000</a>

%H Paolo P. Lava, <a href="/A375078/a375078.pdf">Digit charts for the first 20000 terms</a>

%H Paolo P. Lava, <a href="/A375078/a375078_1.pdf">First 1000 terms</a>

%H Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_1182.htm">Puzzle 1182. Another sequence by Paolo Lava</a>, The Prime Puzzles and Problems Connection.

%p P:=proc(q) local a,b,c,n; a:=[1]; b:=[1];

%p for n from 2 to q do c:=numboccur(n mod 10,b); a:=[op(a),c];

%p if c=0 then b:=[op(b),0]; else b:=[op(b),op(convert(c,base,10))]; fi; od;

%p print(op(a)); end: P(10^3);

%o (Python)

%o from itertools import count, islice

%o def agen(): # generator of terms

%o     s = "1"

%o     yield 1

%o     for n in count(2):

%o         an = s.count(str(n%10))

%o         s += str(an)

%o         yield an

%o print(list(islice(agen(), 82))) # _Michael S. Branicky_, Aug 02 2024

%o (Python)

%o from collections import Counter

%o def A375078_gen(): # generator of terms

%o     c, n = Counter({1:1}), 1

%o     yield 1

%o     while True:

%o         n = (n+1)%10

%o         yield c[n]

%o         c += Counter(map(int,str(c[n])))

%o A375078_list = list(islice(A375078_gen(),30)) # _Chai Wah Wu_, Aug 03 2024

%Y Cf. A136706-A136714.

%K nonn,base,easy

%O 1,10

%A _Paolo P. Lava_, Jul 29 2024