A375742 a(n) = numerator(b(n)), where b(n) = b(n-1)/(1 + b(n-2)) with b(0) = 0 and b(1) = 1.

0, 1, 1, 1, 1, 1, 2, 4, 12, 20, 140, 2380, 30940, 4053140, 976806740, 1800254821820, 61120451455610820, 9679503282638355804820, 644895289728732254890713095060, 11032242225369970870930018496422256556580, 123023889999524997120705110893674654359714272362614340

Offset

0,7

Comments

b(n) = b(n-1)/(1 + b(n-2)) is Pielou's delayed discrete logistic difference equation with unit lag and unit parameters.

References

E. C. Pielou, Population and Community Ecology: Principles and Methods, Gordon and Breach, Science Publishers, Inc. (1974). See p. 80.

Links

Table of n, a(n) for n=0..20.

Mathematica

b[0]=0; b[1]=1; b[n_]:=b[n-1]/(1+b[n-2]); a[n_]:= Numerator[b[n]]; Array[a, 21, 0]

Crossrefs

Cf. A127679 (denominators with offset 2).

Sequence in context: A319213 A099603 A319615 * A343865 A376006 A062767

Adjacent sequences: A375739 A375740 A375741 * A375743 A375744 A375745

Keyword

nonn,easy,frac

Author

Stefano Spezia, Aug 26 2024

Status

approved