OFFSET
1,5
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
FORMULA
MATHEMATICA
PROG
(Magma)
A023531:= func< n | IsIntegral((Sqrt(8*n+9) - 3)/2) select 1 else 0 >;
A023533:= func< n | Binomial(Floor((6*n-1)^(1/3)) +2, 3) ne n select 0 else 1 >;
(SageMath)
@CachedFunction
def A023531(n): return 1 if ((sqrt(8*n+9) -3)/2).is_integer() else 0
@CachedFunction
def A023533(n): return 0 if binomial( floor((6*n-1)^(1/3)) +2, 3)!=n else 1
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved