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A337063 a(n) = 1 for n < 2; a(n) = freq(a(n-1),n) * freq(a(n-2),n) for n >= 2, where freq(i,j) is the number of times i appears in [a(0),a(1),...,a(j-1)]. 2
1, 1, 4, 2, 1, 3, 3, 4, 4, 9, 3, 3, 16, 4, 4, 25, 5, 1, 4, 24, 6, 1, 5, 10, 2, 2, 9, 6, 4, 14, 7, 1, 6, 18, 3, 5, 15, 3, 6, 24, 8, 2, 4, 32, 8, 2, 10, 10, 9, 9, 16, 8, 6, 15, 10, 8, 16, 12, 3, 7, 14, 4, 18, 18, 9, 15, 15, 16, 16, 25, 10, 10, 36, 6, 6, 49, 7, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Does this sequence contain every number?

Does each number appear only a finite number of times?

Starting with a(0)=0 and a(1)=1 gives the same sequence offset by one place.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 0..25000

Rémy Sigrist, PARI program for A337063

EXAMPLE

a(2) = occurrences of a(1)=1 in [a(0), a(1)]=[1, 1] * occurrences of a(0)=1 in [a(0), a(1)]=[1, 1] = 2*2 = 4.

a(3) = occurrences of a(2)=4 in [a(0), a(1), a(2)]=[1, 1, 4] * occurrences of a(1)=1 in [a(0), a(1), a(2)]=[1, 1, 4] = 1*2 = 2.

PROG

(PARI) See Links section.

CROSSREFS

Cf. A337064 (index of first occurrence of n).

Cf. A316774 (which adds the two previous terms), A316973.

Sequence in context: A010124 A271310 A071406 * A010311 A326485 A023528

Adjacent sequences:  A337060 A337061 A337062 * A337064 A337065 A337066

KEYWORD

nonn

AUTHOR

Alex Lauber, Aug 13 2020

EXTENSIONS

More terms from Rémy Sigrist, Sep 18 2020

STATUS

approved

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Last modified June 15 02:56 EDT 2021. Contains 345042 sequences. (Running on oeis4.)