OFFSET
1,3
COMMENTS
Johnson square pyramid: Square base with four equilateral triangular-faces. All the edge lengths are equal to n.
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..1000
Wikipedia, Square pyramid
FORMULA
a(n) = floor(n^3*sqrt(2)/6)
EXAMPLE
a(9)=171: Volume= sqrt(2)/6*n^3= sqrt(2)/6*9^3= 171.8269478 and floor(171.8269478)= 171.
MAPLE
MATHEMATICA
Table[Floor[k^3*Sqrt[2]/6], {k, 1, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
K. D. Bajpai, Sep 17 2013
STATUS
approved