A121360 Smallest k such that A002217(k)=n.

2, 1, 8, 14, 26, 62, 134, 393, 1257, 4659, 9314, 27933, 167073, 334142, 4677862, 14033577, 56134292, 2133102298, 11788191218, 52541651594, 536226160966, 2681130804805, 8512643845707, 129535245187539

Offset

1,1

Comments

Least number which becomes prime or 0 or 4 after n-1 iterations of f(x) = sum of prime factors of x (cf. A001414). Agrees with A048133 except for the second term.

a(21) <= 536226160966. a(22) <= 2681130804805. a(23) <= 8512643845707. - Donovan Johnson, Oct 16 2010

a(25) <= 1679460336114602. - Danila Potapov, Dec 01 2024

Links

Table of n, a(n) for n=1..24.

Crossrefs

Cf. A002217, A001414, A048133.

Sequence in context: A088960 A263528 A379543 * A199928 A047688 A372385

Adjacent sequences: A121357 A121358 A121359 * A121361 A121362 A121363

Keyword

nonn,more

Author

Klaus Brockhaus, Jul 27 2006

Extensions

a(19)-a(20) from Donovan Johnson, Oct 16 2010

a(21)-a(24) from Danila Potapov, Dec 01 2024

Status

approved