A080033 - OEIS

A080033

a(n) is taken to be the smallest positive integer not already present which is consistent with the condition "n is a member of the sequence if and only if a(n) is a multiple of 4".

0, 2, 4, 5, 8, 12, 7, 16, 20, 10, 24, 13, 28, 32, 15, 36, 40, 18, 44, 21, 48, 52, 23, 56, 60, 26, 64, 29, 68, 72, 31, 76, 80, 34, 84, 37, 88, 92, 39, 96, 100, 42, 104, 45, 108, 112, 47, 116, 120, 50, 124, 53, 128, 132, 55, 136, 140, 58, 144, 61, 148, 152, 63, 156, 160, 66

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..65.

B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence, J. Integer Seqs., Vol. 6 (2003), #03.2.2.

B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence (math.NT/0305308)

FORMULA

a(8m)=20m, a(8m+1)=8m+2, a(8m+2)=20m+4, a(8m+3)=8m+5, a(8m+4)=20m+8, a(8m+5)=20m+12, a(8m+6)=8m+7, a(8m+7)=20m+16.

From Chai Wah Wu, Sep 27 2016: (Start)

a(n) = 2*a(n-8) - a(n-16) for n > 15.

G.f.: x*(4*x^14 + x^13 + 8*x^12 + 12*x^11 + 3*x^10 + 16*x^9 + 6*x^8 + 20*x^7 + 16*x^6 + 7*x^5 + 12*x^4 + 8*x^3 + 5*x^2 + 4*x + 2)/(x^16 - 2*x^8 + 1). (End)

CROSSREFS

Cf. A079000, A080030, A080032, A079313, A080034.

Sequence in context: A295032 A280017 A080136 * A007379 A080588 A032850

Adjacent sequences: A080030 A080031 A080032 * A080034 A080035 A080036

KEYWORD

easy,nonn

AUTHOR

N. J. A. Sloane, Mar 14 2003

EXTENSIONS

More terms from Matthew Vandermast, Mar 23 2003

STATUS

approved