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A283529 The number of partitions of n into simple parts. 2

%I

%S 1,1,2,2,3,3,5,5,7,7,9,9,12,12,15,15,18,18,22,22,26,26,30,30,35,35,40,

%T 40,45,45,52,52,59,59,66,66,75,75,84,84,93,93,104,104,115,115,126,126,

%U 139,139,152,152,165,165,180,180,195,195,210,210,228,228

%N The number of partitions of n into simple parts.

%C Number of partitions of n where each part is simple, meaning that each part is in A002110.

%H Giovanni Resta, <a href="/A283529/b283529.txt">Table of n, a(n) for n = 0..10000</a>

%H J. Wang, <a href="http://www.fq.math.ca/Scanned/31-4/wang.pdf">Reduced phi-partitions of positive integers</a>, Fib. Quart. 31 (4) (1993) 365-369.

%F G.f.: 1/Product_{i>=0} (1-x^A002110(i)).

%e a(6)=5 counts 1+1+1+1+1+1 = 1+1+1+2 = 1+1+2+2 = 2+2+2 =6.

%e a(7)=5 counts 1+1+1+1+1+1+1 = 1+1+1+1+1+2 = 1+1+1+2+2 = 1+2+2+2 = 1+6.

%p isA002110 := proc(n)

%p member(n,[1, 2, 6, 30, 210, 2310, 30030, 510510, 9699690, 223092870, 6469693230, 200560490130, 7420738134810, 304250263527210, 13082761331670030, 614889782588491410, 32589158477190044730, 1922760350154212639070]) ;

%p end proc:

%p A283529 := proc(n)

%p local a,k,issimp,p ;

%p a := 0 ;

%p for k in combinat[partition](n) do

%p issimp := true ;

%p for p in k do

%p if not isA002110(p) then

%p issimp := false;

%p break;

%p end if;

%p end do:

%p if issimp then

%p a := a+1 ;

%p end if;

%p end do:

%p a ;

%p end proc:

%t (* It suffices to compute 3 primorials to get 100 correct terms *)

%t terms = 100; primorials = FoldList[Times, 1, Prime[Range[3]]]; 1/(Times @@ (1 - x^primorials)) + O[x]^terms // CoefficientList[#, x]& (* _Jean-Fran├žois Alcover_, May 19 2018 *)

%Y Cf. A002110, A064986, A283528.

%K nonn

%O 0,3

%A _R. J. Mathar_, Mar 10 2017

%E a(0)=1 prepended by _Alois P. Heinz_, Mar 13 2017

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Last modified January 19 17:59 EST 2020. Contains 331051 sequences. (Running on oeis4.)