login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A061117 Maximum number of divisors for any composite between prime(n) and prime(n+1). 3
3, 4, 4, 6, 5, 6, 6, 8, 8, 9, 8, 8, 6, 10, 8, 12, 8, 8, 12, 8, 10, 12, 12, 9, 8, 8, 12, 10, 16, 8, 12, 8, 15, 12, 12, 12, 8, 16, 10, 18, 8, 14, 9, 12, 16, 16, 12, 12, 8, 12, 20, 8, 18, 12, 16, 16, 12, 16, 8, 18, 18, 12, 16, 12, 16, 20, 12, 12, 12, 8, 24, 12, 16, 12, 16, 18, 15, 16, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Michael De Vlieger, Table of n, a(n) for n = 2..10000 (terms up to n = 1000 by Harry J. Smith)

FORMULA

a(n)=Max{d(c); p(n+1)>c>p(n)}, c is composite, p(n) is the n-th prime and d=A000005()

EXAMPLE

p(30)=113 is followed by 13 composites; numbers of divisors are {8, 4, 6, 6, 4, 4, 16, 3, 4, 4, 6, 4, 12}, The smallest is 4=a(30) and the largest is 16.

MATHEMATICA

Max /@ DivisorSigma[0, Select[SplitBy[Range@ Prime@ 81, PrimeQ], CompositeQ@ First@ # &]] (* Michael De Vlieger, Nov 02 2017 *)

PROG

(PARI) { n=-1; q=3; forprime (p=5, prime(1003), a=0; for (i=q + 1, p - 1, a=max(numdiv(i), a)); q=p; write("b061117.txt", n++, " ", a) ) } [From Harry J. Smith, Jul 18 2009]

CROSSREFS

Cf. A000005, A061112.

Sequence in context: A279678 A222283 A182487 * A290820 A111234 A255171

Adjacent sequences:  A061114 A061115 A061116 * A061118 A061119 A061120

KEYWORD

nonn

AUTHOR

Labos Elemer, May 29 2001

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 19 08:51 EST 2017. Contains 294923 sequences.