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A332046 a(n) is the smallest positive integer such that there exist exactly n positive integers less than a(n) whose digital sum in base 10 is equal to the digital sum of a(n). 0

%I #16 Apr 23 2020 12:17:37

%S 10,20,30,40,50,60,70,80,90,108,117,126,135,144,153,162,171,180,207,

%T 216,225,234,243,252,261,270,280,307,316,325,334,343,352,361,370,406,

%U 415,424,433,442,451,460,470,506,515,524,533,542,551,560,605,614,623,632,641,650,660

%N a(n) is the smallest positive integer such that there exist exactly n positive integers less than a(n) whose digital sum in base 10 is equal to the digital sum of a(n).

%e For n=10, 108 is the smallest positive integer for which there exists exactly 10 smaller integers whose digit sum in base 10 is the same as the digit sum of 108 (i.e., 1+0+8=9). These integers are 9, 18, 27, 36, 45, 54, 63, 72, 81, 90.

%o (PARI) isok(k, n) = {my(v=vector(k, j, sumdigits(j))); #select(x->(x==v[k]), v) == n+1;}

%o a(n) = {my(k=1); while(! isok(k, n), k++); k;} \\ _Michel Marcus_, Feb 16 2020

%Y Cf. A081926 (similar but different definition).

%K nonn,base

%O 1,1

%A _Arnauld Chevallier_, Feb 06 2020

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Last modified March 4 22:06 EST 2024. Contains 370532 sequences. (Running on oeis4.)