A304085 Divisor-or-multiple permutation of natural numbers: a(n) = A052330(A304083(n)).

1, 2, 6, 3, 24, 12, 4, 8, 120, 60, 20, 5, 40, 10, 30, 15, 840, 420, 140, 35, 7, 280, 70, 14, 210, 105, 21, 168, 84, 28, 56, 7560, 42, 1890, 945, 315, 63, 9, 3780, 1260, 252, 36, 2520, 630, 126, 18, 1512, 756, 189, 27, 378, 54, 1080, 540, 180, 45, 360, 90, 270, 135, 83160, 504, 72, 216, 108, 41580, 13860, 3465, 693, 99, 11, 27720, 6930, 1386, 198, 22, 20790

Offset

0,2

Comments

Each a(n) is always either a divisor or a multiple of a(n+1).

Links

Antti Karttunen, Table of n, a(n) for n = 0..16383

Index entries for sequences that are permutations of the natural numbers

Formula

a(n) = A052330(A304083(n)).

Prog

(PARI)
up_to_e = 16; \\ Good for computing up to n = (2^16)-1
v050376 = vector(up_to_e);
ispow2(n) = (n && !bitand(n, n-1));
i = 0; for(n=1, oo, if(ispow2(isprimepower(n)), i++; v050376[i] = n); if(i == up_to_e, break));
A050376(n) = v050376[n];
A052330(n) = { my(p=1, i=1); while(n>0, if(n%2, p *= A050376(i)); i++; n >>= 1); (p); };
A304085(n) = A052330(A304083(n)); \\ Needs also code from A304083

Crossrefs

Cf. A304086 (inverse).

Cf. A304083, A304087.

Cf. also A064736, A113552, A207901, A281978, A282291, A302350, A302781, A302783, A303751, A303771 for similar permutations.

Sequence in context: A377876 A206493 A359256 * A302783 A364318 A008306

Adjacent sequences: A304082 A304083 A304084 * A304086 A304087 A304088

Keyword

nonn

Author

Antti Karttunen, May 06 2018

Status

approved