OFFSET
1,2
COMMENTS
The integer that is at the k-th row of the middle column of this pyramid of order n will be noted T(n,k).
Each row has n terms.
FORMULA
EXAMPLE
Triangle begins:
n=1: 1;
n=2: 2, 4;
n=3: 3, 7, 19;
n=4: 4, 10, 28, 78;
n=5: 5, 13, 37, 105, 301;
n=6: 6, 16, 46, 132, 382, 1108;
...
For n=5, the reverse pyramid summation is as follows and row 5 here is the middle column 5,13,37,...
1 2 3 4 5 4 3 2 1
6 9 12 13 12 9 6
27 34 37 34 27
98 105 98
301
PROG
(PARI) f(v) = if (#v == 1, v, vector(#v-2, i, v[i]+v[i+1]+v[i+2]));
row(n) = my(u = concat([1..n], Vecrev([1..n-1])), v=u, w = vector(n)); for (i=1, n, w[i] = v[#v\2+1]; v = f(v); ); w; \\ Michel Marcus, Jan 30 2023
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Bernard Schott, Jan 27 2023
STATUS
approved