login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A317092 Positive integers whose prime multiplicities are weakly decreasing and span an initial interval of positive integers. 4
2, 3, 5, 6, 7, 10, 11, 12, 13, 14, 15, 17, 19, 20, 21, 22, 23, 26, 28, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 51, 52, 53, 55, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 76, 77, 78, 79, 82, 83, 84, 85, 86, 87, 89 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..25000

MATHEMATICA

normalQ[m_]:=Union[m]==Range[Max[m]];

Select[Range[2, 100], And[normalQ[FactorInteger[#][[All, 2]]], OrderedQ[Reverse[FactorInteger[#][[All, 2]]]]]&]

PROG

(PARI) is(n) = my (f=factor(n), w=#f~); if (w==0 || f[w, 2]!=1, return (0), for (k=1, w-1, if (f[k, 2]!=f[k+1, 2] && f[k, 2]!=1+f[k+1, 2], return (0)))

; return (1)) \\ Rémy Sigrist, Sep 05 2018

CROSSREFS

Cf. A001222, A007916, A055932, A056239, A112798, A124010, A133808, A242031.

Cf. A317087, A317088, A317089, A317090, A317091.

Sequence in context: A119316 A336360 A102750 * A225354 A166111 A004762

Adjacent sequences:  A317089 A317090 A317091 * A317093 A317094 A317095

KEYWORD

nonn

AUTHOR

Gus Wiseman, Jul 21 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 24 21:50 EDT 2021. Contains 345433 sequences. (Running on oeis4.)