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 1-7 of 7 results.

A018802 Smallest power of 2 that begins with n.

Original entry on oeis.org

1, 2, 32, 4, 512, 64, 70368744177664, 8, 9007199254740992, 1024, 1125899906842624, 128, 131072, 140737488355328, 151115727451828646838272, 16, 17179869184, 18014398509481984, 19342813113834066795298816, 2048, 2147483648
Offset: 1

Views

Author

David W. Wilson

Keywords

Examples

			a(7) = 70368744177664, because 2^46 is the smallest power of 2 that begins with a 7.

References

  • A. M. Yaglom and I. M. Yaglom, Challenging Mathematical Problems With Elementary Solutions, Vol. 1 pp. 29, 199-200; Prob. 91a, Dover NY 1987

Links

Crossrefs

Cf. A018856.
Cf. this sequence (k=2), A018857 (k=3), A018859 (k=4), A018861 (k=5), A018863 (k=6), A018865 (k=7), A018867 (k=8), A018869 (k=9).

Programs

  • R
    library(gmp); ndig<-function(i) nchar(as.character(as.bigz(i))) y=as.bigz(rep(0,100)); for(i in 1:100) {n=as.bigz(2); while(substr(n,1,ndig(i))!=as.character(i)) n=n*2; y[i]=n; } # Christian N. K. Anderson, May 23 2013

Formula

a(n) = 2^A018856(n). - Seiichi Manyama, Jan 29 2017
a(2^n) = 2^n for n >= 0. - Seiichi Manyama, Jan 29 2017

A018869 Smallest power of 9 that begins with n.

Original entry on oeis.org

1, 282429536481, 387420489, 4782969, 59049, 6561, 729, 81, 9, 109418989131512359209, 11972515182562019788602740026717047105681, 12157665459056928801, 1350851717672992089
Offset: 1

Views

Author

David W. Wilson

Keywords

Links

Crossrefs

Cf. A018802 (k=2), A018857 (k=3), A018859 (k=4), A018861 (k=5), A018863 (k=6), A018865 (k=7), A018867 (k=8), this sequence (k=9).

Formula

a(n) = 9^A018870(n). - Seiichi Manyama, Jan 29 2017
a(9^n) = 9^n for n >= 0. - Seiichi Manyama, Jan 29 2017

A018861 Smallest power of 5 that begins with n.

Original entry on oeis.org

1, 25, 3125, 48828125, 5, 625, 78125, 88817841970012523233890533447265625, 9765625, 108420217248550443400745280086994171142578125, 11920928955078125, 125, 1387778780781445675529539585113525390625, 1490116119384765625, 15625
Offset: 1

Views

Author

David W. Wilson

Keywords

Links

Crossrefs

Cf. A018802 (k=2), A018857 (k=3), A018859 (k=4), this sequence (k=5), A018863 (k=6), A018865 (k=7), A018867 (k=8), A018869 (k=9).

Formula

a(n) = 5^A018862(n). - Seiichi Manyama, Jan 29 2017
a(5^n) = 5^n for n >= 0. - Seiichi Manyama, Jan 29 2017

A018857 Smallest power of 3 that begins with n.

Original entry on oeis.org

1, 27, 3, 4782969, 59049, 6561, 729, 81, 9, 10460353203, 1162261467, 129140163, 1350851717672992089, 14348907, 1594323, 16677181699666569, 177147, 1853020188851841, 19683, 205891132094649, 2187, 22876792454961
Offset: 1

Views

Author

David W. Wilson

Keywords

Links

Crossrefs

Cf. A018802 (k=2), this sequence (k=3), A018859 (k=4), A018861 (k=5), A018863 (k=6), A018865 (k=7), A018867 (k=8), A018869 (k=9).

Formula

a(n) = 3^A018858(n). - Seiichi Manyama, Jan 29 2017
a(3^n) = 3^n for n >= 0. - Seiichi Manyama, Jan 29 2017

A018859 Smallest power of 4 that begins with n.

Original entry on oeis.org

1, 256, 302231454903657293676544, 4, 5070602400912917605986812821504, 64, 70368744177664, 81129638414606681695789005144064, 91343852333181432387730302044767688728495783936, 1024, 1125899906842624
Offset: 1

Views

Author

David W. Wilson

Keywords

Links

Crossrefs

Cf. A018802 (k=2), A018857 (k=3), this sequence (k=4), A018861 (k=5), A018863 (k=6), A018865 (k=7), A018867 (k=8), A018869 (k=9).

Formula

a(n) = 4^A018860(n). - Michel Marcus, Feb 24 2016
a(4^n) = 4^n for n >= 0. - Seiichi Manyama, Jan 29 2017

A018863 Smallest power of 6 that begins with n.

Original entry on oeis.org

1, 216, 36, 46656, 50021738714629030177311081962496059484833406150976385567830453518336, 6, 7776, 80204967233062404407033075859456
Offset: 1

Views

Author

David W. Wilson

Keywords

Comments

a(9) = 6^176, approximately 9.007827639*10^136. - Alan Frank, Jan 28 2011
a(10) = 6^9 = 10077696. - N. J. A. Sloane, Jan 28 2011

Links

Crossrefs

Main sequence is A018864.
Cf. A018802 (k=2), A018857 (k=3), A018859 (k=4), A018861 (k=5), this sequence (k=6), A018865 (k=7), A018867 (k=8), A018869 (k=9).

Formula

a(n) = 6^A018864(n). - Seiichi Manyama, Jan 30 2017
a(6^n) = 6^n for n >= 0. - Seiichi Manyama, Jan 30 2017

A018865 Smallest power of 7 that begins with n.

Original entry on oeis.org

1, 2401, 343, 49, 5764801, 678223072849, 7, 823543, 96889010407, 107006904423598033356356300384937784807, 117649, 129934811447123020117172145698449, 13841287201, 1481113296616977741464105532513750734030421355207
Offset: 1

Views

Author

David W. Wilson

Keywords

Links

Crossrefs

Cf. A018802 (k=2), A018857 (k=3), A018859 (k=4), A018861 (k=5), A018863 (k=6), this sequence (k=7), A018867 (k=8), A018869 (k=9).

Formula

a(n) = 7^A018866(n). - Seiichi Manyama, Jan 30 2017
a(7^n) = 7^n for n >= 0. - Seiichi Manyama, Jan 30 2017

Extensions

One more term (a(14)) from Harvey P. Dale, Mar 04 2014
Showing 1-7 of 7 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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