A396620 a(n) = r(n,n), where r(1,k)=f(k)=ceiling(k*c), r(n,k)=f(r(n-1,k)), c=Pi.

4, 22, 101, 406, 1590, 5866, 21458, 79008, 279184, 961538, 3283383, 11245705, 38041395, 128601451, 439329246, 1469925794, 4882077829, 16229507415, 53512583955, 176314746136, 581275979475, 1931941926271, 6342886318697, 20699787617422, 67785725560417

Offset

1,1

Comments

a(n + 1)/a(n) approaches c erratically.

Links

Table of n, a(n) for n=1..25.

Mathematica

c = Pi; f[k_] := f[k] = Ceiling[c*k];
r[1, k_] := f[k]; r[n_, k_] := r[n, k] = f[r[n - 1, k]];
Table[r[n, n], {n, 1, 100}]

Crossrefs

Cf. A396385, A396619, A396621.

Sequence in context: A366759 A007901 A368289 * A254861 A088581 A017970

Adjacent sequences: A396617 A396618 A396619 * A396621 A396622 A396623

Keyword

nonn

Author

Clark Kimberling, Jun 03 2026

Status

approved