A174014
Deleham triangle [1,1,-1,1,1,-1,1,...] DELTA [1,0,0,1,0,0,1,0,...], DELTA defined in A084938.
Original entry on oeis.org
1, 1, 1, 2, 3, 1, 3, 7, 5, 1, 4, 13, 15, 7, 1, 4, 19, 33, 26, 9, 1, 2, 19, 53, 66, 40, 11, 1, -3, 3, 51, 115, 115, 57, 13, 1, -10, -37, -19, 103, 215, 183, 77, 15, 1, -14, -89, -193, -120, 173, 364, 273, 100, 17, 1, -4, -91, -387, -664, -406, 252, 574, 388, 126, 19, 1
Offset: 0
Triangle begins
1,
1, 1,
2, 3, 1,
3, 7, 5, 1,
4, 13, 15, 7, 1,
4, 19, 33, 26, 9, 1,
2, 19, 53, 66, 40, 11, 1,
-3, 3, 51, 115, 115, 57, 13, 1,
-10, -37, -19, 103, 215, 183, 77, 15, 1,
-14, -89, -193, -120, 173, 364, 273, 100, 17, 1
A174017
A (1,1) Somos-4 sequence.
Original entry on oeis.org
1, 2, -3, 1, 11, -16, -35, -129, 299, -386, -3977, 8063, 42489, 269344, -1000009, 3727745, 47166649, -123526014, -1764203419, -18228952703, 113727892147, -1065812586544, -18344075481339, 52130069331199, 2470319425874195
Offset: 0
-
I:=[1,2,-3,1]; [n le 4 select I[n] else (Self(n-1)*Self(n-3) + Self(n-2)^2)/Self(n-4): n in [1..30]]; // G. C. Greubel, Sep 18 2018
-
RecurrenceTable[{a[n] == (a[n-1]*a[n-3] +a[n-2]^2)/a[n-4], a[0] == 1, a[1] == 2, a[2] == -3, a[3] == 1}, a, {n, 0, 150}] (* G. C. Greubel, Sep 18 2018 *)
nxt[{a_,b_,c_,d_}]:={b,c,d,(b*d+c^2)/a}; NestList[nxt,{1,2,-3,1},30][[All,1]] (* Harvey P. Dale, Jun 21 2022 *)
-
m=30; v=concat([1,2,-3,1], vector(m-4)); for(n=5, m, v[n] = ( v[n-1]*v[n-3] +v[n-2]^2)/v[n-4]); v \\ G. C. Greubel, Sep 18 2018
Showing 1-2 of 2 results.
Comments