OFFSET
1,1
COMMENTS
An alternative representation of k is k = 3*q*r*(q+r), with q, r positive integers, then k is a multiple of 6.
FORMULA
a(n) = 6 * A121741(n).
EXAMPLE
60 is in the sequence because 60 = 5^3 - 4^3 - 1^3, with 5 = 4 + 1.
PROG
(PARI) ok(n) = {my(i=1, a=0, m=0, j); if(n%6==0, while(a<=n&&m==0, j=1; while(j<i&&m==0, a=3*i*j*(i-j); if(a==n, m=1); j+=1); i+=1)); m}
CROSSREFS
KEYWORD
nonn
AUTHOR
Antonio Roldán, Apr 06 2020
STATUS
approved