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

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A008335 Number of primes dividing p+1 as p runs through the primes. 3
1, 1, 2, 1, 2, 2, 2, 2, 2, 3, 1, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 3, 2, 3, 2, 2, 3, 3, 1, 3, 3, 3, 3, 2, 2, 2, 3, 3, 3, 3, 2, 2, 3, 2, 2, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 2, 3, 2, 3, 3, 3, 2, 3, 2, 2, 3, 3, 3, 3, 2, 3, 3, 2, 4, 2, 3, 3, 4, 2, 2, 3, 3, 3, 3, 2, 4, 2, 3, 3, 2, 3, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

T. D. Noe, Table of n, a(n) for n=1..10000

FORMULA

a(n) = A001221(A008864(n)). - Michel Marcus, Mar 29 2016

MAPLE

for i from 1 to 500 do if isprime(i) then print(nops(factorset(i+1))); fi; od;

PROG

(PARI) a(n) = omega(prime(n)+1); \\ Michel Marcus, Mar 29 2016

CROSSREFS

Cf. A001221, A008864.

Sequence in context: A068212 A064131 A105194 * A106031 A055175 A025819

Adjacent sequences:  A008332 A008333 A008334 * A008336 A008337 A008338

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

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 December 3 12:46 EST 2016. Contains 278734 sequences.