A153814 a(n) = 1001*n.

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

Author

Vincenzo Librandi, Jan 02 2009

Keywords

• nonn
• easy

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

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (2,-1).

Crossrefs

Cf. A018768.

Programs

Magma

[1001*n: n in [1..40]]; // Bruno Berselli, Mar 30 2016

Mathematica

Table[1001 n, {n, 1, 40}] (* Bruno Berselli, Mar 30 2016 *)

PARI

for(n=1, 40, print1(1001*n", ")); \\ Vincenzo Librandi, Feb 26 2012

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