A068507 Highly composite numbers sandwiched between twin primes.

4, 6, 12, 60, 180, 240, 7560, 55440, 110880, 73329656400, 18632716502400, 130429015516800, 48519593772249600, 149602080797769600, 74377068101903920953600, 927967188666725711881005276648000, 241271469053348685089061371928480000

Offset

1,1

Comments

Intersection of (A072826 - 1) and (A072828 + 1). - Lekraj Beedassy, Nov 27 2003

The next term, a(18), is A002182(1002), it has 77 digits. - M. F. Hasler, Jun 23 2019

a(22) > 10^17030, if it exists. - Amiram Eldar, Dec 03 2020

Links

M. F. Hasler and Amiram Eldar, Table of n, a(n) for n = 1..21 (terms 1..20 from M. F. Hasler)

Brian Hayes, Does having prime neighbors make you more composite?, Bit-Player Article, Nov 04 2021

Formula

a(n) = A002182(A321995(n)). - Amiram Eldar, Dec 03 2020

Example

60 is between 59 and 61.

Crossrefs

Cf. A002182, A072826, A072828, A117825, A321995.

This is also the intersection of A002182 and A014574.

Sequence in context: A154666 A050537 A114413 * A133454 A061072 A130435

Adjacent sequences: A068504 A068505 A068506 * A068508 A068509 A068510

Keyword

nonn

Author

Lekraj Beedassy, Mar 25 2002

Extensions

Corrected and extended by Lior Manor Jun 03 2002

More terms from Bill McEachen, May 24 2006

a(18)-a(20) from M. F. Hasler, Jun 23 2019

Status

approved