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A101424
Number of different cuboids with volume p^4 * q^n, where p,q are distinct prime numbers.
4
4, 9, 18, 28, 42, 57, 76, 96, 120, 145, 174, 204, 238, 273, 312, 352, 396, 441, 490, 540, 594, 649, 708, 768, 832, 897, 966, 1036, 1110, 1185, 1264, 1344, 1428, 1513, 1602, 1692, 1786, 1881, 1980, 2080, 2184, 2289, 2398, 2508, 2622, 2737, 2856, 2976, 3100
OFFSET
0,1
COMMENTS
Subsequence of A034836, which gives the number of cuboids for volume n.
FORMULA
a(n) = A034836(2^4*3^n) = A034836(3^4*2^n) = A034836(p^4*q^n) for p,q distinct primes.
From Colin Barker, Mar 28 2014: (Start)
The following is conjectured.
a(n) = (29 + 3*(-1)^n + 36*n + 10*n^2)/8.
a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4).
G.f.: -(x+4)/((x+1)*(x-1)^3). (End)
CROSSREFS
KEYWORD
nonn
AUTHOR
Anthony C Robin, Jan 17 2005
EXTENSIONS
Edited and extended by Ray Chandler, Dec 19 2008
a(0)=4 prepended and g.f. edited by Alois P. Heinz, Oct 05 2016
STATUS
approved