The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A181063 Smallest positive integer with a discrete string of exactly n consecutive divisors, or 0 if no such integer exists. 15
 1, 2, 6, 12, 3960, 60, 420, 840, 17907120, 2520, 411863760, 27720, 68502634200, 447069823200, 360360, 720720, 7600186994400, 12252240, 9524356075634400, 81909462250455840, 1149071006394511200, 232792560, 35621201198229847200, 5354228880, 91351145008363640400 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The word "discrete" is used to describe a string of consecutive divisors that is not part of a longer such string. Does a(n) ever equal 0? a(n) = A003418(n) iff n belongs to A181062; otherwise, a(n) > A003418(n). a(A181062(n)) = A051451(n). LINKS David W. Wilson, Table of n, a(n) for n = 1..1000 EXAMPLE a(5) = 3960 is divisible by 8, 9, 10, 11, and 12, but not 7 or 13. It is the smallest positive integer with a string of 5 consecutive divisors that is not part of a longer string. From Gus Wiseman, Oct 16 2019: (Start) The sequence of terms together with their divisors begins: 1: {1} 2: {1,2} 6: {1,2,3,6} 12: {1,2,3,4,6,12} 3960: {1,2,...,8,9,10,11,12,...,1980,3960} 60: {1,2,3,4,5,6,...,30,60} 420: {1,2,3,4,5,6,7,...,210,420} 840: {1,2,3,4,5,6,7,8,...,420,840} (End) MATHEMATICA tav=Table[Length/@Split[Divisors[n], #2==#1+1&], {n, 10000}]; Table[Position[tav, i][[1, 1]], {i, Split[Union@@tav, #2==#1+1&][[1]]}] (* Assumes there are no zeros. - Gus Wiseman, Oct 16 2019 *) CROSSREFS The version taking only the longest run is A328449. The longest run of divisors of n has length A055874(n). Numbers whose divisors > 1 have no non-singleton runs are A088725. The number of successive pairs of divisors of n is A129308(n). Cf. A000005, A003418, A027750, A060775, A181064, A199970, A328166, A328448. Sequence in context: A007668 A089415 A282974 * A161324 A226603 A116534 Adjacent sequences: A181060 A181061 A181062 * A181064 A181065 A181066 KEYWORD nonn AUTHOR Matthew Vandermast, Oct 07 2010 STATUS approved

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

Last modified June 16 19:52 EDT 2024. Contains 373432 sequences. (Running on oeis4.)