login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A172198
Triangle T(n, k, q) = 1 + abs(c(n,q) - c(k,q))*abs(c(n,q) - c(n-k, q)), where c(n,q) = Product_{j=1..n} (1 - q^j) and q = 2, read by rows.
2
1, 1, 1, 1, 325, 1, 1, 178849, 178849, 1, 1, 1121470273, 1106493697, 1121470273, 1, 1, 65131063096321, 64859828626945, 64859828626945, 65131063096321, 1, 1, 34423599076368353281, 34376183545107456001, 34376383642256188417, 34376183545107456001, 34423599076368353281, 1
OFFSET
0,5
FORMULA
T(n, k, q) = 1 + abs(c(n,q) - c(k,q))*abs(c(n,q) - c(n-k, q)), where c(n,q) = Product_{j=1..n} (1 - q^j) and q = 3.
EXAMPLE
Triangle begins as:
1;
1, 1;
1, 325, 1;
1, 178849, 178849, 1;
1, 1121470273, 1106493697, 1121470273, 1;
1, 65131063096321, 64859828626945, 64859828626945, 65131063096321, 1;
MATHEMATICA
T[n_, k_, q_]:= 1 + Abs[QPochhammer[q, q, n] -QPochhammer[q, q, k]]*Abs[QPochhammer[q, q, n] - QPochhammer[q, q, n-k]];
Table[T[n, k, 3], {n, 0, 10}, {k, 0, n}]//TableForm (* modified by G. C. Greubel, May 06 2021 *)
PROG
(Magma)
c:= func< n, q | n eq 0 select 1 else (&*[1-q^j: j in [1..n]]) >;
T:= func< n, k, q | 1 + Abs(c(n, q) - c(k, q))*Abs(c(n, q) - c(n-k, q)) >;
[T(n, k, 3): k in [0..n], n in [0..10]]; // G. C. Greubel, May 06 2021
(Sage)
from sage.combinat.q_analogues import q_pochhammer
def T(n, k, q): return 1 + abs(q_pochhammer(n, q, q) -q_pochhammer(k, q, q))*abs(q_pochhammer(n, q, q) -q_pochhammer(n-k, q, q))
[[T(n, k, 3) for k in (0..n)] for n in (0..10)] # G. C. Greubel, May 06 2021
CROSSREFS
Cf. A172196 (q=2), this sequence (q=3).
Sequence in context: A202635 A013763 A013887 * A343080 A159976 A253433
KEYWORD
nonn,tabl,less,easy
AUTHOR
Roger L. Bagula, Jan 29 2010
EXTENSIONS
Edited by G. C. Greubel, May 06 2021
STATUS
approved