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A076527 Numbers n such that sopf(n) = sopf(n-1) - sopf(n-2), where sopf(x) = sum of the distinct prime factors of x. 8
8, 66, 2883, 3264, 3552, 13872, 21386, 26896, 29698, 29768, 31980, 36567, 40517, 65305, 72012, 82719, 101639, 110848, 160230, 211646, 237136, 237568, 238303, 242606, 299186, 309960, 378014, 393208, 439105, 445795, 455182, 527078, 570021 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

The sum of the distinct prime factors of 66 is 2 + 3 + 11 = 16; the sum of the distinct prime factors of 65 is 5 + 13 = 18; the sum of the distinct prime factors of 64 is 2; and 16 = 18 - 2. Hence 66 belongs to the sequence.

MATHEMATICA

p[n_] := Apply[Plus, Transpose[FactorInteger[n]][[1]]]; Select[Range[4, 10^5], p[ # ] == p[ # - 1] - p[ # - 2] &]

PROG

(MAGMA) [k:k in [4..571000]| &+PrimeDivisors(k-1) - &+PrimeDivisors(k-2) eq (&+PrimeDivisors(k))]; // Marius A. Burtea, Feb 12 2020

CROSSREFS

Cf. A008472, A075565, A075784, A075846, A076525, A076531, A076532, A076533.

Sequence in context: A121766 A052620 A052669 * A247112 A166815 A166797

Adjacent sequences:  A076524 A076525 A076526 * A076528 A076529 A076530

KEYWORD

nonn

AUTHOR

Joseph L. Pe, Oct 18 2002

EXTENSIONS

Edited and extended by Ray Chandler, Feb 13 2005

STATUS

approved

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Last modified August 9 13:39 EDT 2020. Contains 336323 sequences. (Running on oeis4.)