OFFSET
0,3
COMMENTS
a(n) + floor((n+1)/3) is always a multiple of 3. - Jon E. Schoenfield, May 18 2024
FORMULA
a(n) = (A004164(n)-n)/3.
EXAMPLE
For n=42, 42^3 = 74088 has sum of digits 27 so a(42) = (27 - 42)/3 = -5.
MAPLE
read("transforms"):
A372924 := proc(n)
(digsum(n^3)-n)/3 ;
end proc:
seq(A372924(n), n=0..80) ; # R. J. Mathar, Jul 03 2024
MATHEMATICA
Table[(DigitSum[n^3] - n)/3, {n, 0, 100}] (* Paolo Xausa, Jul 03 2024 *)
PROG
(C)
#include <stdint.h>
#include <stdio.h>
int32_t sumDigits(int64_t num)
{
int32_t sum = 0;
while (num > 0)
{
sum += num % 10;
num /= 10;
}
return sum;
}
int main()
{
for (int64_t i=0; i<10000; ++i)
{
int64_t num = i * i * i;
int32_t sum = sumDigits(num);
printf("%ld, ", (sum - i)/3);
}
return 0;
}
CROSSREFS
KEYWORD
sign,base,easy
AUTHOR
Guy Harari, May 16 2024
STATUS
approved