A071292 Call f(n) the sum of the first n primes then a(n) is the number of squares between f(n) and f(n+1).

1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 2, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 1, 2, 2, 1, 2, 1, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2

Offset: 1

Author

Santi Spadaro, Jun 11 2002

Keywords

• nonn

Comments

a(n)>=1.

Links

• Internet Math. Olympiad, February: Problem 1

Programs

Mathematica

squareQ[n_] := IntegerQ[Sqrt[n]] f[n_] := Sum[Prime[i], {i, 1, n}] a[n_] := Length[Select[Table[i, {i, a[n], a[n + 1]}], squareQ]]