A350140 Nonsquarefree numbers whose prime signature has at least one odd part other the first or last.

60, 84, 120, 132, 140, 150, 156, 168, 204, 220, 228, 240, 260, 264, 270, 276, 280, 294, 300, 308, 312, 315, 336, 340, 348, 364, 372, 378, 380, 408, 420, 440, 444, 456, 460, 476, 480, 490, 492, 495, 516, 520, 528, 532, 540, 552, 560, 564, 572, 580, 585, 588

Offset

1,1

Comments

A number's prime signature (row n of A124010) is the sequence of positive exponents in its prime factorization.

Also Heinz numbers of non-weakly alternating non-strict integer partitions, where we define a sequence to be weakly alternating if it is alternately weakly increasing and weakly decreasing, starting with either. These partitions are counted by A349796. This sequence involves the somewhat degenerate case where no strict increases are allowed.

Links

Table of n, a(n) for n=1..52.

Formula

Complement of A005117 in A349794.

Example

The terms together with their Heinz partitions begin (A-E = 10-14):
     60: (3211)      276: (9211)      420: (43211)
     84: (4211)      280: (43111)     440: (53111)
    120: (32111)     294: (4421)      444: (C211)
    132: (5211)      300: (33211)     456: (82111)
    140: (4311)      308: (5411)      460: (9311)
    150: (3321)      312: (62111)     476: (7411)
    156: (6211)      315: (4322)      480: (3211111)
    168: (42111)     336: (421111)    490: (4431)
    204: (7211)      340: (7311)      492: (D211)
    220: (5311)      348: (A211)      495: (5322)
    228: (8211)      364: (6411)      516: (E211)
    240: (321111)    372: (B211)      520: (63111)
    260: (6311)      378: (42221)     528: (521111)
    264: (52111)     380: (8311)      532: (8411)
    270: (32221)     408: (72111)     540: (322211)

Mathematica

Select[Range[300], !SquareFreeQ[#]&&PrimeNu[#]>1&& !And@@EvenQ/@Take[Last/@FactorInteger[#], {2, -2}]&]

Crossrefs

Including all nonsquarefree numbers gives A013929, complement A005117.

Subsets include A088860 and A110286.

Signatures of this type are counted by A274230, complement A027383.

The strict instead of non-strict version is A336568, counted by A347548.

A version for compositions allowing strict is A349057, counted by A349053.

Allowing strict partitions gives A349794, counted by A349061.

These partitions are counted by A349796.

The complement in nonsquarefree partitions is A350137, counted by A349795.

A000041 = integer partitions, strict A000009.

A001250 = alternating permutations, ranked by A349051, complement A348615.

A003242 = Carlitz (anti-run) compositions.

A025047/A025048/A025049 = alternating compositions, ranked by A345167.

A056239 adds up prime indices, row sums of A112798, row lengths A001222.

A096441 = weakly alternating 0-appended partitions.

A124010 = prime signature, sorted A118914.

A345164 = alternating permutations of prime indices, complement A350251.

A345170 = partitions w/ an alternating permutation, ranked by A345172.

A349052/A129852/A129853 = weakly alternating compositions.

A349056 = weakly alternating permutations of prime indices.

A349058 = weakly alternating patterns, complement A350138.

A349060 = weakly alternating partitions, strong A349801.

A349798 = weakly but not strongly alternating perms of prime indices.

Cf. A000111, A047967, A333213, A335448, A344615, A344653, A345173, A349054, A349059, A349797, A349799.

Sequence in context: A099831 A306222 A138604 * A291125 A337688 A086975

Adjacent sequences: A350137 A350138 A350139 * A350141 A350142 A350143

Keyword

nonn

Author

Gus Wiseman, Dec 25 2021

Status

approved