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A133812 Numbers that are primally tight and have weakly descending powers. 4
1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 15, 16, 17, 19, 23, 24, 25, 27, 29, 30, 31, 32, 35, 36, 37, 41, 43, 45, 47, 48, 49, 53, 59, 60, 61, 64, 67, 71, 72, 73, 77, 79, 81, 83, 89, 96, 97, 101, 103, 105, 107, 109, 113, 120, 121, 125, 127, 128, 131, 135, 137, 139, 143, 144 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

All numbers of the form p_1^k1*p_2^k2*...*p_n^k_n, where k1 >= k2 >= ... >= k_n and the p_i are n successive primes.

Differs from A073491 starting n=16.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

aQ[n_] := Module[{f=FactorInteger[n]}, p=f[[;; , 1]]; e=f[[;; , 2]]; PrimePi[p[[-1]]]-PrimePi[p[[1]]] == Length[p]-1 && AllTrue[Differences[e], #<=0 &]]; Join[{1}, Select[Range[2, 144], aQ]] (* Amiram Eldar, Jun 20 2019 *)

CROSSREFS

Cf. A025487, A087980, A073491, A133808-A133813, A025487.

Sequence in context: A069899 A081306 A130073 * A115661 A318735 A002244

Adjacent sequences:  A133809 A133810 A133811 * A133813 A133814 A133815

KEYWORD

nonn

AUTHOR

Olivier Gérard, Sep 23, 2007

EXTENSIONS

Cross-references from Charles R Greathouse IV, Dec 04 2009

STATUS

approved

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Last modified April 12 21:13 EDT 2021. Contains 342932 sequences. (Running on oeis4.)