login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A024937 a(n) = number of 2's in all partitions of n into distinct primes. 2
0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 3, 3, 2, 3, 3, 3, 4, 3, 5, 4, 4, 5, 5, 6, 6, 5, 7, 7, 7, 8, 8, 9, 8, 9, 11, 11, 10, 12, 12, 13, 14, 14, 16, 15, 16, 17, 19, 20, 20, 20, 22, 24, 23, 26, 27, 27, 28, 30, 33, 34, 34, 36, 37, 40, 41, 43, 46, 46, 47, 50, 55, 56, 56, 58, 63, 64 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,19

LINKS

Table of n, a(n) for n=0..90.

Sean A. Irvine, Java program (github)

FORMULA

G.f.: x^2*Product_{k>1} (1+x^prime(k)). - Vladeta Jovovic, Jul 20 2003

MAPLE

with(numtheory):

b:= proc(n, i) option remember; local g;

    if n=0 then [1, 0]

    elif i<1 then [0, 0]

    else g:= `if`(ithprime(i)>n, [0$2], b(n-ithprime(i), i-1));

         b(n, i-1) +g +[0, `if`(i=1, g[1], 0)]

    fi

end:

a:= n-> b(n, pi(n))[2]:

seq(a(n), n=0..80);  # Sean A. Irvine, after Alois P. Heinz, Jul 29 2019

CROSSREFS

Cf. A024939.

Sequence in context: A255472 A230198 A024939 * A143977 A115265 A105223

Adjacent sequences:  A024934 A024935 A024936 * A024938 A024939 A024940

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

More terms from Vladeta Jovovic, Jul 20 2003

a(0)-a(6) prepended by Sean A. Irvine, Jul 29 2019

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 21 04:42 EDT 2021. Contains 343146 sequences. (Running on oeis4.)