A231969 a(n) = the smallest squarefree number (A005117) with n prime factors in a 2p+1 progression.

2, 10, 110, 2530, 118910, 17036047229140531, 4713753689937227789548410467592773787730621935419, 4754361703029497628070972207349674154455369685904736544199583856401, 17434718204270642890620908753958444038404912529730635812020757976125828120134034469

Offset

1,1

Comments

Smallest squarefree numbers with n >= 2 prime divisors of the form p_1 * p_2 * … * p_n, where p_1 < p_2 < … < p_k = primes with p_k = 2 * p_(k-1) + 1.

Links

Jaroslav Krizek, Table of n, a(n) for n = 1..12

Example

17036047229140531 = 89*179*359*719*1439*2879, where 179 = 2*89 + 1, 359 = 2*179 + 1, 719 = 2*359 + 1, 1439 = 2*719 + 1, 2879 = 2*1439 + 1.

Crossrefs

Cf. A005117, A000040, A231966, A231967, A231968.

Sequence in context: A335946 A206154 A181445 * A062499 A305854 A234296

Adjacent sequences: A231966 A231967 A231968 * A231970 A231971 A231972

Keyword

nonn

Author

Jaroslav Krizek, Nov 16 2013

Status

approved