[go: up one dir, main page]

login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Nonprime Heinz numbers of superperiodic integer partitions.
3

%I #7 Sep 15 2018 15:46:31

%S 9,25,27,49,81,121,125,169,243,289,343,361,441,529,625,729,841,961,

%T 1331,1369,1521,1681,1849,2187,2197,2209,2401,2809,3125,3249,3481,

%U 3721,4225,4489,4913,5041,5329,6241,6561,6859,6889,7569,7921,8281,9261,9409,10201

%N Nonprime Heinz numbers of superperiodic integer partitions.

%C A subsequence of A001597.

%C A number n is in the sequence iff n = 2 or the prime indices of n have a common divisor > 1 and the Heinz number of the multiset of prime multiplicities of n, namely A181819(n), is already in the sequence.

%C The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).

%e The sequence of partitions whose Heinz numbers belong to the sequence begins: (22), (33), (222), (44), (2222), (55), (333), (66), (22222), (77), (444), (88), (4422), (99), (3333), (222222).

%t supperQ[n_]:=Or[n==2,And[GCD@@PrimePi/@FactorInteger[n][[All,1]]>1,supperQ[Times@@Prime/@FactorInteger[n][[All,2]]]]];

%t Select[Range[10000],And[!PrimeQ[#],supperQ[#]]&]

%Y Cf. A001597, A056239, A072774, A181819, A182850, A289509, A296150, A298748, A304464, A305732, A317246, A317257, A319149, A319151.

%K nonn

%O 1,1

%A _Gus Wiseman_, Sep 12 2018