|
|
A191000
|
|
Greedy inverse of A034690: the smallest number m such that sum of digits of all divisors of m equals n; a(n) = 0 if no such number exists.
|
|
2
|
|
|
1, 0, 2, 3, 13, 5, 4, 7, 10, 0, 19, 6, 9, 21, 8, 403, 79, 34, 12, 39, 35, 16, 129, 38, 133, 52, 30, 100, 28, 18, 81, 63, 24, 75, 333, 66, 64, 117, 99, 243, 76, 60, 889, 171, 88, 36, 279, 54, 484, 387, 78, 48, 475, 136, 1209, 208, 132, 729, 112, 258, 225, 84, 90, 399, 1396, 162, 741, 796
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
LINKS
|
|
|
EXAMPLE
|
a(5) = 13 because 13 is the smallest number such that sum of digits of all its divisors is equal to 5: 1 + 1 + 3 = 5.
a(2) = a(10) = 0 because there is no number such that sum of digits of all its divisors is equal to 2 or 10.
|
|
PROG
|
(PARI) sdd(n) = sumdiv(n, d, sumdigits(d)); \\ A034690
a(n) = if ((n==2) || (n==10), return (0)); my(k=1); while (sdd(k) != n, k++); k; \\ Michel Marcus, Oct 06 2021
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|