A071182 SPF(n+1)-SPF(n), where SPF(n) denotes the smallest prime factor of n.

1, -1, 3, -3, 5, -5, 1, -1, 9, -9, 11, -11, 1, -1, 15, -15, 17, -17, 1, -1, 21, -21, 3, -3, 1, -1, 27, -27, 29, -29, 1, -1, 3, -3, 35, -35, 1, -1, 39, -39, 41, -41, 1, -1, 45, -45, 5, -5, 1, -1, 51, -51, 3, -3, 1, -1, 57, -57, 59, -59, 1, -1, 3, -3, 65, -65, 1, -1, 69, -69, 71, -71, 1, -1, 5, -5, 77, -77, 1, -1, 81, -81, 3, -3, 1

Offset: 2

Author

Joseph L. Pe, Jun 10 2002

Keywords

• sign

Programs

Mathematica

g[n_] := (FactorInteger[n])[[1]][[1]]; f[n_] := g[n + 1] - g[n]; Table[f[i], {i, 2, 100}]