A175214 a(1)=1; for n > 1, a(n) = a(floor(sqrt(n))) + a(floor(sqrt(n-1))).

1, 2, 2, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8

Offset

1,2

Links

Table of n, a(n) for n=1..90.

Example

a(1)  = 1,
a(2)  = a(1) + a(1) = 2,
a(3)  = a(1) + a(1) = 2,
a(4)  = a(2) + a(1) = 3,
a(5)  = a(2) + a(2) = 4,
a(6)  = a(2) + a(2) = 4,
a(7)  = a(2) + a(2) = 4,
a(8)  = a(2) + a(2) = 4,
a(9)  = a(3) + a(2) = 4,
a(10) = a(3) + a(3) = 4,
a(11) = a(3) + a(3) = 4, etc.

Prog

(PARI) a(n) = if (n==1, 1, my(r=sqrtint(n), s=sqrtint(n-1)); a(r) + a(s)); \\ Michel Marcus, Mar 17 2022

Crossrefs

Cf. A000196.

Sequence in context: A065167 A332298 A300404 * A368700 A095395 A029134

Adjacent sequences: A175211 A175212 A175213 * A175215 A175216 A175217

Keyword

easy,nonn

Author

Ctibor O. Zizka, Mar 06 2010

Extensions

More terms from Michel Marcus, Mar 17 2022

Name simplified by Jon E. Schoenfield, Mar 17 2022

Status

approved