A174809 A (100,-196) Somos 4 sequence.

1, 4, 68, 3664, 559296, 292983296, 677028302848, 5742750182014976, 140199451387306704896, 10334993471103615132237824, 3076052900280004094541239943168, 3864163084421857020112275272686895104

Offset: 0

Author

Paul Barry, Mar 29 2010

Keywords

• easy
• nonn

Comments

Hankel transform of A174808.

Links

• G. C. Greubel, Table of n, a(n) for n = 0..60

Programs

Magma

I:=[1,4,68,3664]; [n le 4 select I[n] else (100*Self(n-1)*Self(n-3) - 196*Self(n-2)^2)/Self(n-4): n in [1..20]]; // G. C. Greubel, Sep 18 2018

Mathematica

RecurrenceTable[{a[n] == (100*a[n-1]*a[n-3] -196*a[n-2]^2)/a[n-4], a[0] == 1, a[1] == 4, a[2] == 68, a[3] == 3664}, a, {n, 0, 20}] (* G. C. Greubel, Sep 18 2018 *)

PARI

m=20; v=concat([1,4,68,3664], vector(m-4)); for(n=5, m, v[n] = ( 100*v[n-1]*v[n-3] - 196*v[n-2]^2)/v[n-4]); v \\ G. C. Greubel, Sep 18 2018

Formula

a(n) = (100*a(n-1)*a(n-3) - 196*a(n-2)^2)/a(n-4), n>3.