A121615 Lexicographically earliest sequence such that the k-th prime occurs altogether not more than k times as prime factor.

2, 3, 5, 7, 11, 13, 15, 17, 19, 23, 29, 31, 35, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 121, 127, 131, 137, 139, 143, 149, 151, 157, 163, 167, 169, 173, 179, 181, 187, 191, 193, 197, 199, 211, 221, 223, 227, 229, 233, 239

Offset

1,1

Comments

Subsequence of A037143: 1 <= A001222(a(n)) <= 2; A000040 is a subsequence.

Links

R. Zumkeller, Table of n, a(n) for n = 1..1000

Example

k=1, prime(1)=2: {2} = {a(1)},
k=2, prime(2)=3: {3,3*5} = {a(2),a(7)},
k=3, prime(3)=5: {5,3*5,5*7} = {a(3),a(7),a(13)},
k=4, prime(4)=7: {7,5*7,7*7} = {a(4),a(7),a(18)},
k=5, prime(5)=11: {11,11*11,11*13,11*17} = {a(5),a(34),a(39),a(49)},
k=6, prime(6)=13: {13,11*13,13*13,13*17,13*19} = {a(6),a(39),a(45),a(55),a(62)};
k=7, prime(7)=17: {17,11*17,13*17,17*17,17*19,17*23} = {a(8),a(49),a(55),a(71),a(77),a(90)}.

Crossrefs

Sequence in context: A003277 A322833 A117287 * A097605 A143578 A187731

Adjacent sequences: A121612 A121613 A121614 * A121616 A121617 A121618

Keyword

nonn

Author

Reinhard Zumkeller, Aug 11 2006

Status

approved