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A332290
Heinz numbers of widely alternately co-strongly normal integer partitions.
8
1, 2, 4, 6, 8, 12, 16, 30, 32, 60, 64, 128, 210, 256, 360, 512, 1024, 2048, 2310, 2520, 4096, 8192, 16384, 30030, 32768, 65536, 75600, 131072, 262144, 510510, 524288
OFFSET
1,2
COMMENTS
An integer partition is widely alternately co-strongly normal if either it is constant 1's (wide) or it covers an initial interval of positive integers (normal) and has weakly increasing run-lengths (co-strong) which, if reversed, are themselves a widely alternately co-strongly normal partition.
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).
This sequence is closed under A181821, so there are infinitely many terms that are not powers of 2 or primorial numbers.
EXAMPLE
The sequence of all widely alternately co-strongly normal integer partitions together with their Heinz numbers begins:
1: ()
2: (1)
4: (1,1)
6: (2,1)
8: (1,1,1)
12: (2,1,1)
16: (1,1,1,1)
30: (3,2,1)
32: (1,1,1,1,1)
60: (3,2,1,1)
64: (1,1,1,1,1,1)
128: (1,1,1,1,1,1,1)
210: (4,3,2,1)
256: (1,1,1,1,1,1,1,1)
360: (3,2,2,1,1,1)
512: (1,1,1,1,1,1,1,1,1)
1024: (1,1,1,1,1,1,1,1,1,1)
2048: (1,1,1,1,1,1,1,1,1,1,1)
2310: (5,4,3,2,1)
2520: (4,3,2,2,1,1,1)
For example, starting with y = (4,3,2,2,1,1,1), which has Heinz number 2520, and repeatedly taking run-lengths and reversing gives (4,3,2,2,1,1,1) -> (3,2,1,1) -> (2,1,1) -> (2,1) -> (1,1). These are all normal with weakly increasing run-lengths and the last is all 1's, so 2520 belongs to the sequence.
MATHEMATICA
primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
totnQ[ptn_]:=Or[ptn=={}, Union[ptn]=={1}, And[Union[ptn]==Range[Max[ptn]], LessEqual@@Length/@Split[ptn], totnQ[Reverse[Length/@Split[ptn]]]]];
Select[Range[10000], totnQ[Reverse[primeMS[#]]]&]
CROSSREFS
Closed under A181821.
The non-co-strong version is A332276.
The enumeration of these partitions by sum is A332289.
The total (rather than alternating) version is A332293.
Sequence in context: A344181 A242101 A131117 * A332293 A181821 A241882
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, Feb 14 2020
STATUS
approved