A154796 - OEIS

%I #16 Apr 03 2019 18:51:11

%S 30,56,176,490,792,1958,3010,6842,89134,124754,451276,614154,831820,

%T 2012558,8118264,13848650,133230930,214481126,271248950,541946240,

%U 851376628,1327710076,3163127352,4835271870,5964539504,7346629512

%N Even partition numbers of odd numbers.

%C Even numbers in A058695.

%H Alois P. Heinz, <a href="/A154796/b154796.txt">Table of n, a(n) for n = 1..1000</a>

%e The even number 30 is in the sequence as the partition number of the odd number 9. - _Emeric Deutsch_, Aug 02 2009

%p aa:= proc(n, i) if n=0 then 1 elif n<0 or i=0 then 0 else aa(n,i):= aa(n, i-1) +aa(n-i, i) fi end: a:= proc(n) local k; if n>1 then a(n-1) fi; for k from `if`(n=1, 1, b(n-1)+2) by 2 while irem(aa(k, k), 2)=1 do od; b(n):= k; aa(k, k) end: seq(a(n), n=1..40); # _Alois P. Heinz_, Jul 28 2009

%p with(combinat): a := proc (n) if `mod`(numbpart(2*n-1), 2) = 0 then numbpart(2*n-1) else end if end proc: seq(a(n), n = 1 .. 70); # _Emeric Deutsch_, Aug 02 2009

%t Reap[Do[If[EvenQ[p = PartitionsP[n]], Sow[p]], {n, 1, 199, 2}]][[2, 1]] (* _Jean-François Alcover_, Nov 11 2015 *)

%t Select[PartitionsP[Range[1,201,2]],EvenQ] (* _Harvey P. Dale_, Apr 03 2019 *)

%o (PARI) lista(nn) = for (n=1, nn, if (((p = numbpart(2*n+1)) % 2) == 0, print1(p, ", "))); \\ _Michel Marcus_, Dec 19 2016

%Y Cf. A000041, A005408, A058695, A154795, A154797, A154798.

%K nonn

%O 1,1

%A _Omar E. Pol_, Jan 26 2009

%E More terms from _Alois P. Heinz_, Jul 28 2009