A325266 -id:A325266 - cp's OEIS frontend

A325246 Number of integer partitions of n with adjusted frequency depth equal to their length.

1, 1, 2, 1, 2, 2, 4, 4, 6, 8, 14, 15, 21, 26, 34, 42, 51, 60, 74, 86, 102, 117, 137, 155, 178, 202, 228, 255, 286, 317, 355, 390, 430, 472, 519, 566, 617, 670, 728, 787, 852, 916, 988, 1060, 1137, 1218, 1303, 1389, 1482, 1577, 1679, 1781, 1890, 2001, 2120

Offset: 0

Gus Wiseman, Apr 15 2019

nonn

The Heinz numbers of these partitions are given by A325266.

The adjusted frequency depth of an integer partition is 0 if the partition is empty, and otherwise it is 1 plus the number of times one must take the multiset of multiplicities to reach a singleton. For example, the partition (32211) has adjusted frequency depth 5 because we have: (32211) -> (221) -> (21) -> (11) -> (2). The enumeration of integer partitions by adjusted frequency depth is given by A325280. The adjusted frequency depth of the integer partition with Heinz number n is given by A323014.

			The a(1) = 1 through a(10) = 14 partitions (A = 10):
  (1)  (2)   (3)  (4)   (5)     (6)     (7)     (8)      (9)      (A)
       (11)       (22)  (2111)  (33)    (421)   (44)     (432)    (55)
                                (321)   (2221)  (431)    (531)    (532)
                                (3111)  (4111)  (521)    (621)    (541)
                                                (5111)   (3222)   (631)
                                                (32111)  (6111)   (721)
                                                         (32211)  (3331)
                                                         (42111)  (4222)
                                                                  (7111)
                                                                  (32221)
                                                                  (33211)
                                                                  (42211)
                                                                  (43111)
                                                                  (52111)

Cf. A001222, A008284, A127002, A181819, A182850, A225485, A323014, A323023, A325254, A325266, A325277, A325280, A325281.

fdadj[ptn_List]:=If[ptn=={},0,Length[NestWhileList[Sort[Length/@Split[#]]&,ptn,Length[#]>1&]]];
Table[Length[Select[IntegerPartitions[n],fdadj[#]==Length[#]&]],{n,0,30}]

A325281 Numbers of the form ab, aab, or aabc where a, b, and c are distinct primes. Numbers with sorted prime signature (1,1), (1,2), or (1,1,2).

Original entry on oeis.org

6, 10, 12, 14, 15, 18, 20, 21, 22, 26, 28, 33, 34, 35, 38, 39, 44, 45, 46, 50, 51, 52, 55, 57, 58, 60, 62, 63, 65, 68, 69, 74, 75, 76, 77, 82, 84, 85, 86, 87, 90, 91, 92, 93, 94, 95, 98, 99, 106, 111, 115, 116, 117, 118, 119, 122, 123, 124, 126, 129, 132

Offset: 1

Gus Wiseman, Apr 18 2019

nonn

Also numbers whose adjusted frequency depth is one plus their number of prime factors counted with multiplicity. The adjusted frequency depth of a positive integer n is 0 if n = 1, and otherwise it is one plus the number of times one must apply A181819 to reach a prime number, where A181819(k = p^i*...*q^j) = prime(i)*...*prime(j) = product of primes indexed by the prime exponents of k. For example, 180 has adjusted frequency depth 5 because we have: 180 -> 18 -> 6 -> 4 -> 3.

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k), so these are Heinz numbers of integer partitions whose adjusted frequency depth is equal to their length plus 1. The enumeration of these partitions by sum is given by A127002.

			The sequence of terms together with their prime indices and their omega-sequences (see A323023) begins:
   6:     {1,2} (2,2,1)
  10:     {1,3} (2,2,1)
  12:   {1,1,2} (3,2,2,1)
  14:     {1,4} (2,2,1)
  15:     {2,3} (2,2,1)
  18:   {1,2,2} (3,2,2,1)
  20:   {1,1,3} (3,2,2,1)
  21:     {2,4} (2,2,1)
  22:     {1,5} (2,2,1)
  26:     {1,6} (2,2,1)
  28:   {1,1,4} (3,2,2,1)
  33:     {2,5} (2,2,1)
  34:     {1,7} (2,2,1)
  35:     {3,4} (2,2,1)
  38:     {1,8} (2,2,1)
  39:     {2,6} (2,2,1)
  44:   {1,1,5} (3,2,2,1)
  45:   {2,2,3} (3,2,2,1)
  46:     {1,9} (2,2,1)
  50:   {1,3,3} (3,2,2,1)
  51:     {2,7} (2,2,1)
  52:   {1,1,6} (3,2,2,1)
  55:     {3,5} (2,2,1)
  57:     {2,8} (2,2,1)
  58:    {1,10} (2,2,1)
  60: {1,1,2,3} (4,3,2,2,1)

Cf. A056239, A112798, A118914, A127002, A181819, A323023, A325246, A325259, A325266, A325270, A325277, A325282.

Omega-sequence statistics: A001222 (first omega), A001221 (second omega), A071625 (third omega), A323022 (fourth omega), A304465 (second-to-last omega), A182850 or A323014 (length/frequency depth), A325248 (Heinz number), A325249 (sum).

fdadj[n_Integer]:=If[n==1,0,Length[NestWhileList[Times@@Prime/@Last/@FactorInteger[#]&,n,!PrimeQ[#]&]]];
Select[Range[100],fdadj[#]==PrimeOmega[#]+1&]

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A325246 Number of integer partitions of n with adjusted frequency depth equal to their length.

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A325281 Numbers of the form ab, aab, or aabc where a, b, and c are distinct primes. Numbers with sorted prime signature (1,1), (1,2), or (1,1,2).

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cp's OEIS Frontend

A325246 Number of integer partitions of n with adjusted frequency depth equal to their length.

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A325281 Numbers of the form a*b, a*a*b, or a*a*b*c where a, b, and c are distinct primes. Numbers with sorted prime signature (1,1), (1,2), or (1,1,2).

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A325281 Numbers of the form ab, aab, or aabc where a, b, and c are distinct primes. Numbers with sorted prime signature (1,1), (1,2), or (1,1,2).