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A346035 a(1) = 1; if a(n) is not divisible by 3, a(n+1) = 4*a(n) + 1, otherwise a(n+1) = a(n)/3. 1
1, 5, 21, 7, 29, 117, 39, 13, 53, 213, 71, 285, 95, 381, 127, 509, 2037, 679, 2717, 10869, 3623, 14493, 4831, 19325, 77301, 25767, 8589, 2863, 11453, 45813, 15271, 61085, 244341, 81447, 27149, 108597, 36199, 144797, 579189, 193063, 772253, 3089013, 1029671, 4118685 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Tristan Young, Table of n, a(n) for n = 1..15000

Tristan Young, C code to generate a b-file for the first 15000 terms of this sequence

MATHEMATICA

a[1] = 1; a[n_] := a[n] = If[Divisible[a[n-1], 3], a[n-1]/3, 4*a[n-1]+1]; Array[a, 50] (* Amiram Eldar, Jul 12 2021 *)

PROG

(Processing)

// generates all the numbers in the sequence before it first surpasses 1 billion

int n;

void setup() {

n = 1;

noLoop();

}

void draw() {

print(n + ", ");

while (true) {

if (n % 3 == 0) {

n /= 3;

} else {

n *= 4; n++;

}

print(n);

if (n == 1 || n >= 600000000) {

break;

} else {

print(", ");

}

}

}

(PARI) a(n) = if (n==1, 1, my(x=a(n-1)); if (x % 3, 4*x+1, x/3)); \\ Michel Marcus, Aug 12 2021

CROSSREFS

Cf. A006370, A128333, A153727.

Sequence in context: A156824 A053002 A053003 * A167202 A204914 A355036

Adjacent sequences: A346032 A346033 A346034 * A346036 A346037 A346038

KEYWORD

easy,nonn

AUTHOR

Tristan Young, Jul 02 2021

STATUS

approved

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Last modified December 3 08:35 EST 2022. Contains 358515 sequences. (Running on oeis4.)