A232169 Squarefree numbers (A005117) with prime factors in a prime(k) + k progression.

6, 15, 30, 77, 247, 4819, 7979, 10057, 12827, 21353, 24047, 40363, 60433, 121411, 146231, 154729, 211763, 273509, 301297, 322499, 346781, 367063, 382937, 394091, 415693, 453727, 485237, 486719, 579727, 632579, 803017, 874219, 910073, 1009823, 1013333, 1218053

Offset

1,1

Comments

Let p(m) = prime(m), let i(p(m)) = m, the subscript of p(m); a(n) = squarefree numbers with k>=2 prime factors of the form p_1 * p_2 * p_3 * ... * p_k, where p_1 < p_2 < p_3 < ... < p_k with p_k = p_(k-1) + i(p_(k-1)).

Supersequence of A232170.

Links

Table of n, a(n) for n=1..36.

Example

30 = 2*3*5; p_1 = 2, p_2 = 2+1 = 3, p_3 = 3+2 = 5 (2 = 1st prime, 3 = 2nd prime).

Crossrefs

Cf. A000040, A005117, A232170, A232171.

Sequence in context: A212251 A262464 A353695 * A231814 A056497 A278033

Adjacent sequences: A232166 A232167 A232168 * A232170 A232171 A232172

Keyword

nonn

Author

Jaroslav Krizek, Nov 19 2013

Status

approved