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A328985 First differences of A328984. 3
2, 4, -2, 6, -3, 9, -7, 11, -8, 14, -12, 16, -13, 19, -17, 21, -18, 24, -22, 26, -23, 29, -27, 31, -28, 34, -32, 36, -33, 39, -37, 41, -38, 44, -42, 46, -43, 49, -47, 51, -48, 54, -52, 56, -53, 59, -57, 61, -58, 64, -62, 66, -63, 69, -67, 71, -68, 74 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This is a simplified version of A328196.

Conjecture: satisfies a linear recurrence having signature (-1, 0, 0, 1, 1). - Harvey P. Dale, Apr 06 2021

LINKS

Table of n, a(n) for n=1..58.

FORMULA

If n is a multiple of 4 then a(n) = 5*t+1 where t = n/4;

if n is 2 mod 4 then a(n) = 5*t+4 where t = (n-2)/4;

if n is 1 mod 4 then a(n) = -(5*t-2) where t = (n-1)/4;

if n i s 3 mod 4 then a(n) = -(5*t+2) where t = (n-3)/4.

From Colin Barker, Nov 07 2019: (Start)

G.f.: x*(2 + 6*x + 2*x^2 + 4*x^3 + x^4) / ((1+x)*(1-x^4)).

a(n) = -a(n-1) + a(n-4) + a(n-5) for n>5.

(End)

MATHEMATICA

Differences[Table[Which[EvenQ[n], Floor[(5 n/2+1)/2], Mod[n, 4]==1, 10 (n-1)/4+1, True, 10 (n-3)/4+7], {n, 70}]] (* Harvey P. Dale, Apr 06 2021 *)

CROSSREFS

Cf. A328190, A328196, A328984.

Sequence in context: A230436 A105393 A182812 * A328196 A323307 A215841

Adjacent sequences:  A328982 A328983 A328984 * A328986 A328987 A328988

KEYWORD

sign,changed

AUTHOR

N. J. A. Sloane, Nov 06 2019

STATUS

approved

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Last modified April 19 00:18 EDT 2021. Contains 343098 sequences. (Running on oeis4.)