This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A120120 Number of n-digit prime quadruplets. 3
 1, 3, 7, 26, 128, 733, 3869, 23620, 152141, 1028789, 7188960, 51672312, 381226246, 2873279651 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 LINKS J.-L. Baril, Classical sequences revisited with permutations avoiding dotted pattern, Electronic Journal of Combinatorics, 18 (2011), #P178. T. R. Nicely, Enumeration to 1.6*10^15 of the prime quadruplets. EXAMPLE a(3) = 3 because there are three three-digit prime quadruples: {101, 103, 107, 109}, {191, 193, 197, 199} and {821, 823, 827, 829}. CROSSREFS Cf. A006879, A070076, A038801. Sequence in context: A158561 A252786 A108217 * A126472 A019059 A305446 Adjacent sequences:  A120117 A120118 A120119 * A120121 A120122 A120123 KEYWORD nonn,more,base AUTHOR Julien Peter Benney (jpbenney(AT)ftml.net), Aug 15 2006, Aug 19 2006 EXTENSIONS a(6) corrected and a(15) supplied by Jon E. Schoenfield, Aug 27 2006 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 5 10:45 EST 2019. Contains 329751 sequences. (Running on oeis4.)