OFFSET
1,4
LINKS
Vincenzo Librandi, Rows n = 1..50, flattened
EXAMPLE
The array starts in row n=1 with columns k>=1 as
1, 1, 2, 2, 6, 6, 18, 16, 48, 60, A011260
1, 2, 4, 8, 22, 48, 156, 320, 1008, 2640, A027385
2, 4, 20, 48, 280, 720, 5580, 14976, 99360, 291200, A027741
2, 8, 36, 160, 1120, 6048, 37856, 192000, 1376352, 8512000, A027743
4,16, 144, 960, 12880, 62208,1087632,7027200,85098816,691398400,
4,24, 240, 1536, 24752, 224640,2988024,21934080
MAPLE
A := proc(n, k) local p ; p := ithprime(n) ; if k = 0 then 1; else numtheory[phi](p^k-1)/k ; end if; end proc:
MATHEMATICA
t[n_, k_] := If[k == 0, 1, p = Prime[n]; EulerPhi[p^k - 1]/k]; Flatten[ Table[t[n - k + 1, k], {n, 1, 11}, {k, 1, n}]] (* Jean-François Alcover, Jun 04 2012, after Maple *)
CROSSREFS
KEYWORD
AUTHOR
R. J. Mathar, Aug 29 2011
STATUS
approved