cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 13 results. Next

A330486 Earliest start of a run of n numbers divisible by a seventh power larger than one.

Original entry on oeis.org

128, 76544, 2372890624, 390491792890623, 2083234733888734218749, 18962123650219836035505781245
Offset: 1

Views

Author

Jud McCranie, Dec 15 2019

Keywords

Comments

In De Koninck's book, a(4) was probable but not certain. It also gives probable terms for a(5) and a(6).
From David A. Corneth, Dec 18 2019: (Start)
a(6) <= 18962123650219836035505781245
a(7) <= 105574810222799317012520534891328125
a(8) <= 352061173826332779662070232460962002804453118
a(9) <= 74322635218313783849790472504951802188239215127109371
If any a(k) of these values are less than presented values, one of a(k) + m is divisible only by at least one p^7 for some p > 31, 0 <= m < k.
For a(6) this minimum prime is some prime p > 59. (End)

Examples

			2372890624 is divisible by 2^7, 2372890625 is divisible by 5^7, 2372890626 is divisible by 3^7.  This is the smallest number with this property, so a(3)=2372890624.
		

References

  • J.-M. De Koninck, Those Fascinating Numbers, Entry 242, p. 63, Amer. Math. Soc., 2009.

Crossrefs

Extensions

a(5) from Giovanni Resta, Dec 17 2019
a(6) from Giovanni Resta, Dec 19 2019

A330483 Earliest start of a run of n numbers divisible by an eighth power larger than one.

Original entry on oeis.org

256, 636416, 70925781248, 36430999887109373, 5031679407516945387109374
Offset: 1

Views

Author

Jud McCranie, Dec 16 2019

Keywords

Comments

Similar to sequences in the crossreferences.
a(6) <= 330987813033061096652260864453120. - Robert Israel, Jun 02 2020

Examples

			70925781248 is divisible by 2^8, 70925781249 is divisible by 3^8, 70925781250 is divisible by 5^8. This is the smallest number with this property, so a(3) = 70925781248.
		

Crossrefs

Extensions

a(4) from Giovanni Resta, Dec 16 2019
a(5) from Giovanni Resta, Dec 17 2019

A330480 Earliest start of a run of n numbers divisible by a fourth power larger than one.

Original entry on oeis.org

16, 80, 33614, 202099373, 40280549372, 430995495889374, 77405340617896874
Offset: 1

Views

Author

Jud McCranie, Dec 16 2019

Keywords

Comments

De Koninck's book says that "most likely" a(7)=77405340617896874.

Examples

			33614 is divisible by 7^4, 33615 is divisible by 3^4, and 33616 is divisible by 2^4.  This is the smallest number with this property, so a(3)=33614.
		

References

  • J.-M. De Koninck, Those Fascinating Numbers, Entry 242, p. 63, Amer. Math. Soc., 2009.

Crossrefs

Extensions

a(7) from Giovanni Resta, Dec 18 2019

A330481 Earliest start of a run of n numbers divisible by a fifth power larger than one.

Original entry on oeis.org

32, 1215, 2590623, 2146909373, 105636978090621, 3269698976575137500
Offset: 1

Views

Author

Jud McCranie, Dec 15 2019

Keywords

Comments

De Koninck's book gives probable a(6) = 3269698976575137500.
a(7) <= 745436945776920355709374. - Giovanni Resta, Dec 19 2019

Examples

			1215 is divisible by 3^5 and 1216 is divisible by 2^5. This is the smallest number with this property, so a(2)=1215.
		

References

  • J.-M. De Koninck, Those Fascinating Numbers, Entry 242, p. 63, Amer. Math. Soc., 2009.

Crossrefs

Extensions

a(6) from Giovanni Resta, Dec 19 2019

A330482 Earliest start of a run of n numbers divisible by a sixth power larger than one.

Original entry on oeis.org

64, 16767, 26890623, 1507545109375, 777562026420218750, 283435321166212288109372
Offset: 1

Views

Author

Jud McCranie, Dec 16 2019

Keywords

Comments

De Konnick's book gives probable terms a(5)=777562026420218750 and a(6)=283435321166212288109372.

Examples

			26890623 is divisible by 3^6, 26890624 is divisible by 2^6, and 26890625 is divisible by 5^6.  This is the smallest number with this property, so a(3) = 26890623.
		

References

  • J.-M. De Koninck, Those Fascinating Numbers, Entry 242, p. 63, Amer. Math. Soc., 2009.

Crossrefs

Extensions

a(5) from Giovanni Resta, Dec 17 2019
a(6) from Giovanni Resta, Dec 19 2019

A330484 Earliest start of a run of n numbers divisible by a ninth power larger than one.

Original entry on oeis.org

512, 3995648, 2889212890624, 18705093636361328125, 19810215665260426138787109374
Offset: 1

Views

Author

Jud McCranie, Dec 16 2019

Keywords

Comments

a(6) <= 39109788784614310863666299138574218749. - Robert Israel, Jun 02 2020

Examples

			2889212890624 is divisible by 2^9, 2889212890625 is divisible by 5^9, and 2889212890626 is divisible by 3^9. This is the smallest number with this property, so a(3)=2889212890624.
		

Crossrefs

Extensions

a(4)-a(5) from Giovanni Resta, Dec 17 2019

A330485 Earliest start of a run of n numbers divisible by a tenth power larger than one.

Original entry on oeis.org

1024, 24151040, 61938212890624, 9226967798833574218749, 13279660499584033124533574218748
Offset: 1

Views

Author

Jud McCranie, Dec 16 2019

Keywords

Examples

			61938212890624 is divisible by 2^10, 61938212890625 is divisible by 5^10, and 61938212890626 is divisible by 3^10.  This is the smallest number with this property, so a(3)=61938212890624.
		

Crossrefs

Extensions

a(4) from Giovanni Resta, Dec 17 2019
a(5) from Giovanni Resta, Dec 19 2019

A271444 Smallest of 4 consecutive numbers each divisible by a cube greater than one.

Original entry on oeis.org

22624, 355374, 885624, 912247, 1558248, 1642624, 1728375, 1761991, 2068373, 2485375, 2948373, 2987872, 3072248, 3073623, 3243750, 3571749, 3744872, 3772248, 3916374, 4231248, 4442877, 4503247, 4730373, 4757750, 5301125, 5344623, 5516125, 5812477, 6017247
Offset: 1

Views

Author

Giovanni Resta, Apr 26 2016

Keywords

Examples

			a(1)=22624 is the smallest cubeful number followed by other 3 cubeful numbers. They are divisible by 2^5, 5^3, 3^3, and 11^3, respectively.
		

Crossrefs

Programs

  • Mathematica
    cubQ[n_] := Max[Last /@ FactorInteger[n]] > 2; Select[Range[10^6], cubQ[#] && cubQ[# + 1] && cubQ[# + 2] && cubQ[# + 3] &]
    SequencePosition[Table[If[AnyTrue[Rest[Divisors[n]],IntegerQ[CubeRoot[#]]&],1,0],{n,61*10^5}],{1,1,1,1}][[;;,1]] (* Harvey P. Dale, Jan 05 2025 *)

Extensions

Definition clarified by Harvey P. Dale, Jan 05 2025

A271445 Smallest of 5 consecutive numbers each divisible by a cube.

Original entry on oeis.org

18035622, 100942496, 133799496, 146447622, 156406624, 185966872, 192779375, 215927748, 314066750, 327879871, 363664375, 377956500, 403254124, 412284624, 422615124, 440799246, 458147500, 520659248, 558732248, 562037373, 634965372, 642252750, 664596248
Offset: 1

Views

Author

Giovanni Resta, Apr 26 2016

Keywords

Examples

			a(1) = 18035622 is the smallest cubeful number followed by other 4 cubeful numbers. They are divisible by 3^4, 17^3, 2^3, 5^4, and 7^3, respectively.
		

Crossrefs

A271446 Smallest of 6 consecutive numbers each divisible by a cube.

Original entry on oeis.org

4379776620, 6329354875, 16620507123, 54089484125, 55072893248, 66519175371, 68769514373, 80566783622, 87372290871, 91351389622, 99156598496, 105748687372, 112806598372, 114265205871, 117243671750, 148257477247, 155970667499, 174404710246, 177398391245
Offset: 1

Views

Author

Giovanni Resta, Apr 26 2016

Keywords

Examples

			a(1) = 4379776620 is the smallest cubeful number followed by other 5 cubeful numbers. They are divisible by 29^3, 11^3, 13^3, 3^3, 2^4, and 5^3, respectively.
		

Crossrefs

Showing 1-10 of 13 results. Next