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

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

A018867 Smallest power of 8 that begins with n.

Original entry on oeis.org

1, 262144, 32768, 4096, 512, 64, 73786976294838206464, 8, 9223372036854775808, 1073741824, 1152921504606846976, 1237940039285380274899124224, 134217728, 144115188075855872, 154742504910672534362390528, 16777216
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), this sequence (k=8), A018869 (k=9).

Formula

a(n) = 8^A018868(n). - Seiichi Manyama, Jan 29 2017
a(8^n) = 8^n for n >= 0. - Seiichi Manyama, Jan 29 2017
Showing 1-7 of 7 results.

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

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