A271950 Somos's sequence {b(5,n)} defined in comment in A078495: a(0)=a(1)=...=a(12)=1; for n>=13, a(n)=(a(n-1)*a(n-12)+a(n-6)*a(n-7))/a(n-13).

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 7, 9, 15, 27, 47, 77, 119, 301, 519, 827, 1351, 2345, 4263, 10598, 35021, 91652, 200923, 396578, 742721, 2258305, 5126953, 14354017, 45716169, 138331649, 377080865, 1330892225, 5490413305, 16470110241

Offset

0,14

Links

Seiichi Manyama, Table of n, a(n) for n = 0..392

Mathematica

a[k_, n_]:=a[k, n]=If[n>2k+2, (a[k, (n-1)]*a[k, (n-2k-2)]+a[k, (n-k-1)]*a[k, (n-k-2)])/a[k, (n-2k-3)], 1];
Map[a[5, #]&, Range[0, 50]] (* Peter J. C. Moses, Apr 17 2016 *)
RecurrenceTable[{a[0]==a[1]==a[2]==a[3]==a[4]==a[5]==a[6]==a[7]== a[8]== a[9]== a[10]== a[11] ==a[12]==1, a[n]==(a[n-1]a[n-12]+a[n-6]a[n-7])/a[n-13]}, a, {n, 50}] (* Harvey P. Dale, May 01 2018 *)

Prog

(PARI) {a(n) = if(n< 12, 1, (a(n-1)*a(n-12) + a(n-6)*a(n-7))/a(n-13))};
for(n=0, 40, print1(a(n), ", ")) \\ G. C. Greubel, Feb 21 2018
(Magma) [n le 13 select 1 else ((Self(n-1)*Self(n-12) + Self(n-6)*Self(n- 7) )/Self(n-13)): n in [1..40]]; // G. C. Greubel, Feb 21 2018

Crossrefs

Cf. A006721, A078495, A268199, A271948, A271949.

Sequence in context: A160339 A033072 A030287 * A263482 A030153 A039126

Adjacent sequences: A271947 A271948 A271949 * A271951 A271952 A271953

Keyword

nonn

Author

Vladimir Shevelev and Peter J. C. Moses, Apr 17 2016

Status

approved