OFFSET
1,18
COMMENTS
For n > 1: if A023961(n)=2 then a(n) = a(n-1) + 1, otherwise a(n) = a(n-1).
Lim_{n->infinity} a(n)/n = 1/10.
REFERENCES
G. Pólya and G. Szegő, Problems and Theorems in Analysis I (Springer 1924, reprinted 1972), Part Two, Chap. 4, Sect. 4, Problem 178.
LINKS
Paolo Xausa, Table of n, a(n) for n = 1..10000
EXAMPLE
a(10) = 1, a(100) = 9, a(1000) = 99, a(10000) = 990.
MATHEMATICA
Accumulate[Array[Boole[Mod[Floor[10*Sqrt[#]], 10] == 2] &, 100]] (* Paolo Xausa, May 17 2024 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Aug 20 2005
STATUS
approved