A161177 Index of first multiple of n-th prime in A005179.

2, 4, 12, 32, 96, 240, 640, 1280, 2560, 9600, 19200, 57344, 114688, 229376, 458752, 1290240, 3145728, 6291456, 13762560, 27525120, 62914560, 134217728, 335544320, 671088640, 1342177280, 2684354560, 5368709120, 10737418240, 26306674688, 52613349376

Offset

1,1

Comments

The numbers are divisible by higher and higher powers of 2 because the numbers in A005179 typically have a "tail" of primes occurring in first power only.

From David A. Corneth, May 01 2024: (Start)

A001222(a(n)) >= n.

What is the smallest term divisible by 11? (End)

Links

Table of n, a(n) for n=1..30.

Formula

a(n) >= 2*a(n-1) for n >= 2. - David A. Corneth, May 01 2024

Example

a(3)=12: The third prime is 5 and A005179(12)=60 is the first multiple of 5 occurring in sequence A005179.

Prog

(PARI) a(n) = my(p=prime(n), k=1); while (A005179(k) % p, k++); k; \\ Michel Marcus, Apr 20 2024

Crossrefs

Cf. A001222, A005179, A007416.

Sequence in context: A025178 A231295 A087211 * A039721 A148193 A341344

Adjacent sequences: A161174 A161175 A161176 * A161178 A161179 A161180

Keyword

nonn,hard,more

Author

Hagen von Eitzen, Jun 05 2009

Extensions

a(13)-a(15) from Michel Marcus, Apr 20 2024

a(16) from Michel Marcus, May 01 2024

a(17)-a(30) from David A. Corneth, May 01 2024

Status

approved