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A120444 First differences of A004125. 10
0, 1, 0, 3, -1, 5, 0, 4, 1, 9, -5, 11, 3, 5, 0, 15, -4, 17, -3, 9, 7, 21, -13, 18, 9, 13, -1, 27, -13, 29, 0, 17, 13, 21, -20, 35, 15, 21, -11, 39, -13, 41, 3, 11, 19, 45, -29, 40, 6, 29, 5, 51, -13, 37, -9, 33, 25, 57, -49, 59, 27, 21, 0, 45, -13, 65, 9, 41, -5, 69, -52, 71, 33, 25, 11, 57, -13, 77, -27, 40, 37, 81, -57, 61, 39, 53, -5 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

It appears that (1) a(n)=0 if and only if n is a power of 2 and (2) a(n)=n-1 if and only if n+1 is a prime. (This has been verified for the first 2000 terms.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A005408(n) - A000203(n+1). - Omar E. Pol, Jan 24 2014

PROG

(Haskell)

a120444 n = a120444_list !! (n-1)

a120444_list = zipWith (-) (tail a004125_list) a004125_list

-- Reinhard Zumkeller, May 30 2015

CROSSREFS

Cf. A000203, A004125, A005408.

Sequence in context: A143315 A237588 A235796 * A094919 A328373 A316631

Adjacent sequences:  A120441 A120442 A120443 * A120445 A120446 A120447

KEYWORD

sign

AUTHOR

John W. Layman, Jul 19 2006

STATUS

approved

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Last modified November 17 06:06 EST 2019. Contains 329217 sequences. (Running on oeis4.)