A343753 Number of partitions of prime(n) containing a prime number of primes.
0, 0, 2, 6, 26, 49, 154, 258, 666, 2404, 3588, 11096, 22477, 31620, 61247, 157725, 387527, 518155, 1208470, 2086019, 2726745, 5975695, 9935799, 20882243, 54355088, 86547260, 108874661, 171286370, 214236058, 333331046, 1486031972, 2246585402, 4132451733
Offset: 1
Keywords
Examples
a(4) = 6 because there are 6 partitions of prime(4) = 7 that contain a prime number of primes (including repetitions). These partitions are [5,2], [3,3,1], [3,2,2], [3,2,1,1], [2,2,2,1], [2,2,1,1,1].
Links
- David A. Corneth, Table of n, a(n) for n = 1..700
Programs
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Mathematica
nterms=20;Table[Total[Map[If[PrimeQ[Count[#, _?PrimeQ]],1,0] &,IntegerPartitions[Prime[n]]]],{n,1,nterms}]
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PARI
forprime(p=2, 67, my(m=0); forpart(X=p, my(j=0); for(k=1, #X, if(isprime(X[k]), j++));if(isprime(j),m++)); print1(m, ", ")) \\ Hugo Pfoertner, May 01 2021