A076660 Numbers m such that A076644(m) = floor((2/3)*m*(sqrt(m)+1)).

1, 2, 6, 17, 24, 26, 29, 43, 83, 88, 193, 207, 243, 357, 534, 806, 1082, 1197, 1377, 2246, 2362, 3148, 4342, 4570, 6463, 11687, 14305, 35681, 41369, 53410, 75292, 98348, 146608, 219393, 246121, 257663, 419767, 476246, 596919, 860060, 912227, 1225215, 2239828, 2727103, 2819396

Offset: 1

Author

Benoit Cloitre, Oct 24 2002

Keywords

• nonn

Comments

Sequence is probably infinite.

Links

• Michel Marcus, Table of n, a(n) for n = 1..50

Crossrefs

Cf. A076644.

Programs

PARI

lista(nn) = {my(v=vector(nn)); v[1] = 1; for (n=2, nn, v[n] = n + v[n-sqrtint(n)]; ); for (m=1, nn, if (v[m] == floor((2/3)*m*(sqrt(m)+1)), print1(m, ", ")););} \\ Michel Marcus, Feb 16 2021

Formula

It seems that a(n) is asymptotic to c*exp(d*n) with d around 0.33...

Extensions

Incorrect term 4 removed and more terms added from Michel Marcus, Feb 16 2021