A070872 Numbers k such that A070871(k) = k.

1, 2, 6, 66, 216, 1159, 2184

Offset

1,2

Comments

Could be called nutritionally balanced numbers.

The next term, if it exists, is greater than 1.4 * 10^9. - William P. Orrick, Apr 30 2026

There are no new terms less than 10^10. - David Cleaver, May 12 2026

Links

Table of n, a(n) for n=1..7.

Mathematica

a[0] = 1; a[n_] := a[n] = If[ OddQ[n], a[n/2 - 1/2], a[n/2] + a[n/2 - 1]]; Do[ If[ a[n]*a[n - 1] == n, Print[n]], {n, 1, 5*10^6}]

Crossrefs

Cf. A002487, A070871.

Sequence in context: A193609 A061999 A066756 * A386390 A055685 A368511

Adjacent sequences: A070869 A070870 A070871 * A070873 A070874 A070875

Keyword

nonn,more

Author

J. H. Conway, May 17 2002

Extensions

More terms from David W. Wilson, May 17 2002

Status

approved