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 1-3 of 3 results.

A153814 a(n) = 1001*n.

Original entry on oeis.org

1001, 2002, 3003, 4004, 5005, 6006, 7007, 8008, 9009, 10010, 11011, 12012, 13013, 14014, 15015, 16016, 17017, 18018, 19019, 20020, 21021, 22022, 23023, 24024, 25025, 26026, 27027, 28028, 29029, 30030, 31031, 32032, 33033, 34034, 35035, 36036, 37037, 38038
Offset: 1

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Author

Vincenzo Librandi, Jan 02 2009

Keywords

Comments

Previous name was: 143*7n.
Property of 143*7n shown by Ghersi (see References):
a(n) = n00n for n from 1 to 9;
a(n) = n0n for n from 10 to 99;
a(n) = nn for n from 100 to 999.

References

  • I. Ghersi, Matematica dilettevole e curiosa, Hoepli (1967), p. 138

Links

Crossrefs

Cf. A018768.

Programs

Formula

From Vincenzo Librandi, Feb 26 2012: (Start)
G.f.: 1001*x/(1-x)^2.
a(n) = 2*a(n-1) - a(n-2). (End) [G.f. corrected by Georg Fischer, May 10 2019]
E.g.f.: 1001*x*exp(x). - Elmo R. Oliveira, Apr 10 2025

Extensions

Name changed by Michel Marcus, Mar 30 2016

A027901 Divisors of 10^9 + 1.

Original entry on oeis.org

1, 7, 11, 13, 19, 77, 91, 133, 143, 209, 247, 1001, 1463, 1729, 2717, 19019, 52579, 368053, 578369, 683527, 999001, 4048583, 4784689, 6993007, 7518797, 10989011, 12987013, 52631579, 76923077, 90909091, 142857143, 1000000001
Offset: 1

Views

Author

N. J. A. Sloane

Keywords

Comments

The prime factorization of 10^9 + 1 = 7 * 11 * 13 * 19 * 52579, so tau(1000000001) = 2^5 = 32. - Bernard Schott, Oct 18 2019

Examples

			7 * 142857143 = 1000000001.
11 * 90909091 = 1000000001.
13 * 76923077 = 1000000001.

Links

Crossrefs

Cf. A018768, A133029.

Programs

A133023 Divisors of 2001.

Original entry on oeis.org

1, 3, 23, 29, 69, 87, 667, 2001
Offset: 1

Views

Author

Omar E. Pol, Oct 28 2007

Keywords

Examples

			29*69 = 2001.

Links

Crossrefs

Cf. A018768.

Programs

Showing 1-3 of 3 results.

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

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