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A235049 Subtract one from each nonzero digit in decimal representation of n.

%I A235049 #23 Jan 13 2023 11:05:01
%S A235049 0,0,1,2,3,4,5,6,7,8,0,0,1,2,3,4,5,6,7,8,10,10,11,12,13,14,15,16,17,
%T A235049 18,20,20,21,22,23,24,25,26,27,28,30,30,31,32,33,34,35,36,37,38,40,40,
%U A235049 41,42,43,44,45,46,47,48,50,50,51,52,53,54,55,56,57,58,60
%N A235049 Subtract one from each nonzero digit in decimal representation of n.
%C A235049 Contains exactly the same terms as A007095, except that each occurs an infinite number of times.
%C A235049 A102683(a(n)) = 0. - _Reinhard Zumkeller_, Apr 16 2014
%H A235049 Antti Karttunen, <a href="/A235049/b235049.txt">Table of n, a(n) for n = 0..10000</a>
%H A235049 <a href="/index/De#decimal_expansion">Index entries for sequences related to decimal expansion of n</a>
%F A235049 a(0) = 0, and for n>=1, if n = 0 modulo 10, a(n) = 10*a(n/10), otherwise a(n) = 10*a(floor(n/10)) + (n modulo 10) - 1.
%e A235049 Subtracting one from each nonzero digit of '9', we get 8, thus a(9)=8. Doing same for '10' results '00' thus a(10)=0. For '12', this results '01', thus a(12)=1.
%t A235049 a[n_] := FromDigits[If[#>0, #-1, #]& /@ IntegerDigits[n]];
%t A235049 Table[a[n], {n, 0, 100}] (* _Jean-François Alcover_, Jan 13 2023 *)
%o A235049 (MIT/GNU Scheme, two implementations)
%o A235049 (define (A235049 n) (let loop ((z 0) (i 0) (n n)) (if (zero? n) z (let ((d (modulo n 10))) (loop (+ z (* (expt 10 i) (if (zero? d) d (- d 1)))) (1+ i) (floor->exact (/ n 10)))))))
%o A235049 ;; As a recurrence, using memoization macro definec from _Antti Karttunen_'s IntSeq-library:
%o A235049 (definec (A235049 n) (if (zero? n) n (let ((d (modulo n 10))) (+ (* 10 (A235049 (floor->exact (/ n 10)))) (if (zero? d) d (- d 1))))))
%o A235049 (Haskell)
%o A235049 a235049 x = if x == 0 then 0 else 10 * a235049 x' + max 0 (d - 1)
%o A235049             where (x', d) = divMod x 10
%o A235049 -- _Reinhard Zumkeller_, Apr 16 2014
%Y A235049 Cf. A007095.
%K A235049 nonn,easy,base,look
%O A235049 0,4
%A A235049 _Antti Karttunen_, Apr 14 2014