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.

A062568 a(n) is the smallest n-digit strong pseudoprime (in base 2).

Original entry on oeis.org

2047, 15841, 104653, 1004653, 10323769, 100463443, 1002261781, 10000321321, 100004790097, 1000002977551, 10000130243671, 100002236680837, 1000003918690669, 10000008250001701, 100000150553089531, 1000000274500018837, 10000003599249373469
Offset: 4

Views

Author

Shyam Sunder Gupta, Feb 13 2002

Keywords

Examples

			a(1)=2047 because 2047 is the smallest 4-digit strong pseudoprime to base 2.

Links

Crossrefs

Cf. A001567, A068216, A067845, A001262, A062852.

Extensions

Edited by Charles R Greathouse IV, Nov 01 2009
a(17)-a(20) from Charles R Greathouse IV, Mar 14 2011

A062852 Largest n-digit strong pseudoprimes (in base 2).

Original entry on oeis.org

8321, 90751, 983401, 9995671, 99789673, 999828727, 9998721001, 99973476433, 999855751441, 9998974546471, 99999760517281, 999985147456681, 9999952887414577, 99999984319096601, 999999916795882627, 9999999995077192591
Offset: 4

Views

Author

Shyam Sunder Gupta, Feb 13 2002

Keywords

Examples

			a(4)=8321 since 8321 is the largest 4-digit strong pseudoprime to base 2.

Links

Crossrefs

Cf. A001567, A068216, A067845, A001262, A062568.

Extensions

Edited by Charles R Greathouse IV, Nov 01 2009
a(16)-a(19) from Charles R Greathouse IV, Mar 14 2011

A068216 a(n) is the smallest n-digit pseudoprime (to base 2).

Original entry on oeis.org

341, 1105, 10261, 101101, 1004653, 10004681, 100017223, 1001152801, 10000321321, 100004790097, 1000001376901, 10000130243671, 100000105970311, 1000000191735161, 10000006286491369, 100000010102756401, 1000000114865704261, 10000000494514450733
Offset: 3

Views

Author

Patrick De Geest and Shyam Sunder Gupta, Feb 21 2002

Keywords

Links

Crossrefs

Cf. A001567, A067845, A001262, A062568, A062852.

Extensions

One more term from Farideh Firoozbakht, Jan 10 2007
More terms from Jens Kruse Andersen, May 11 2008
Offset corrected by Arkadiusz Wesolowski, Dec 14 2011

A067869 Numbers n such that n and 2^n end with the same 5 digits.

Original entry on oeis.org

48736, 148736, 248736, 348736, 448736, 548736, 648736, 748736, 848736, 948736, 1048736, 1148736, 1248736, 1348736, 1448736, 1548736, 1648736, 1748736, 1848736, 1948736, 2048736, 2148736, 2248736, 2348736, 2448736, 2548736
Offset: 1

Views

Author

Benoit Cloitre, Mar 07 2002

Keywords

Links

Crossrefs

Cf. A064541.
Subsequence of A067844, A067845, A067846, and A067847.

Programs

  • PARI
    isok(n) = (2^n - n) % 100000 == 0; \\ Michel Marcus, Nov 23 2013

Formula

a(n) = 48736+10^5(n-1).
a(n) = 2*a(n-1)-a(n-2). G.f.: x*(48736+51264*x)/(1-x)^2. - Colin Barker, Jun 05 2012

A067866 Numbers n such that n and 2^n end with the same three digits.

Original entry on oeis.org

736, 1736, 2736, 3736, 4736, 5736, 6736, 7736, 8736, 9736, 10736, 11736, 12736, 13736, 14736, 15736, 16736, 17736, 18736, 19736, 20736, 21736, 22736, 23736, 24736, 25736, 26736, 27736, 28736, 29736, 30736, 31736, 32736, 33736, 34736
Offset: 1

Views

Author

Benoit Cloitre, Mar 07 2002

Keywords

Links

Crossrefs

Cf. A064541.
Subsequence of A067844 and A067845.

Programs

  • PARI
    isok(n) = (2^n - n) % 1000 == 0; \\ Michel Marcus, Nov 23 2013

Formula

a(n) = 736 + 1000(n-1).
a(n) = 2*a(n-1)-a(n-2). G.f.: 8*x*(92+33*x)/(1-x)^2. [Colin Barker, Dec 01 2012]

A067867 Numbers n such that n and 2^n end with the same 4 digits.

Original entry on oeis.org

8736, 18736, 28736, 38736, 48736, 58736, 68736, 78736, 88736, 98736, 108736, 118736, 128736, 138736, 148736, 158736, 168736, 178736, 188736, 198736, 208736, 218736, 228736, 238736, 248736, 258736, 268736, 278736, 288736, 298736, 308736
Offset: 1

Views

Author

Benoit Cloitre, Mar 07 2002

Keywords

Links

Crossrefs

Cf. A064541.
Subsequence of A067844, A067845 and A067846.

Programs

  • PARI
    isok(n) = (2^n - n) % 10000 == 0; \\ Michel Marcus, Nov 23 2013

Formula

a(n) = 8736 + 10^4(n-1).
a(n) = 2*a(n-1)-a(n-2). G.f.: 16*x*(546+79*x)/(1-x)^2. [Colin Barker, Dec 01 2012]

A254519 Largest n-digit pseudoprime to base 3.

Original entry on oeis.org

91, 949, 8911, 97567, 997633, 9959413, 99971821, 999271891, 9999326731, 99997244929, 999989423051, 9999899578441, 99999695823301, 999999050050321, 9999997295187859, 99999997019370001
Offset: 2

Views

Author

Felix Fröhlich, Jan 31 2015

Keywords

Crossrefs

Cf. A005935, A067845.

Programs

  • PARI
    for(n=2, 20, k=10^n; while(ispseudoprime(k) || Mod(3, k)^(k-1)!=1, k--); print1(k, ", "))
Showing 1-7 of 7 results.

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

Content is available under The OEIS End-User License Agreement.