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A090340 Difference between the sums of the prime factors, including multiplicity, of n and those of n + 1. 3
-2, -1, -1, -1, 0, -2, 1, 0, -1, -4, 4, -6, 4, 1, 0, -9, 9, -11, 10, -1, -3, -10, 14, -1, -5, 6, -2, -18, 19, -21, 21, -4, -5, 7, 2, -27, 16, 5, 5, -30, 29, -31, 28, 4, -14, -22, 36, -3, 2, -8, 3, -36, 42, -5, 3, -9, -9, -28, 47, -49, 28, 20, 1, -6, 2, -51, 46, -5, 12, -57, 59, -61, 34, 26, -10, 5, 0, -61, 66, 1, -31, -40, 69, -8, -23, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If a(n) = 0 then n is a Ruth-Aaron number. - Andrew Slattery, Apr 15 2020

LINKS

Table of n, a(n) for n=1..86.

FORMULA

a(n) = sopfr(n) - sopfr(n+1), where sopfr = A001414. - Wesley Ivan Hurt, Aug 10 2016

EXAMPLE

a(24)=-1 because 24=2*2*2*3, 25=5*5 and (2+2+2+3)-(5+5)=-1.

CROSSREFS

Cf. A001414 (sopfr), A090341, A090342, A090343.

Ruth-Aaron numbers: A039752.

Sequence in context: A135997 A026609 A286935 * A287364 A117162 A277045

Adjacent sequences:  A090337 A090338 A090339 * A090341 A090342 A090343

KEYWORD

sign

AUTHOR

Charles K. Layman (cklayman(AT)juno.com), Nov 25 2003

STATUS

approved

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Last modified July 5 19:02 EDT 2020. Contains 335473 sequences. (Running on oeis4.)