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

1,8

Comments

a(n)>=1.

Links

Table of n, a(n) for n=1..100.

Internet Math. Olympiad, February: Problem 1

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]]

Crossrefs

Sequence in context: A109495 A164295 A035214 * A088569 A246144 A192763

Adjacent sequences: A071289 A071290 A071291 * A071293 A071294 A071295

Keyword

nonn

Author

Santi Spadaro, Jun 11 2002

Status

approved