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A071182 SPF(n+1)-SPF(n), where SPF(n) denotes the smallest prime factor of n. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,3

LINKS

Table of n, a(n) for n=2..86.

MATHEMATICA

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

CROSSREFS

Sequence in context: A087852 A087853 A095334 * A197100 A258642 A136027

Adjacent sequences:  A071179 A071180 A071181 * A071183 A071184 A071185

KEYWORD

sign

AUTHOR

Joseph L. Pe, Jun 10 2002

STATUS

approved

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Last modified April 3 14:11 EDT 2020. Contains 333197 sequences. (Running on oeis4.)