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A158407
a(n) = 900*n + 1.
2
901, 1801, 2701, 3601, 4501, 5401, 6301, 7201, 8101, 9001, 9901, 10801, 11701, 12601, 13501, 14401, 15301, 16201, 17101, 18001, 18901, 19801, 20701, 21601, 22501, 23401, 24301, 25201, 26101, 27001, 27901, 28801, 29701, 30601, 31501
OFFSET
1,1
COMMENTS
The identity (900*n + 1)^2 - (900*n^2 + 2*n)*30^2 = 1 can be written as a(n)^2 - A158406(n)*(30)^2 = 1. - Vincenzo Librandi, Feb 09 2012
FORMULA
G.f.: x*(901-x)/(1-x)^2. - Vincenzo Librandi, Feb 09 2012
a(n) = 2*a(n-1) - a(n-2). - Vincenzo Librandi, Feb 09 2012
MATHEMATICA
LinearRecurrence[{2, -1}, {901, 1801}, 50] (* Vincenzo Librandi, Feb 09 2012 *)
900*Range[40]+1 (* Harvey P. Dale, Aug 18 2019 *)
PROG
(Magma) I:=[901, 1801]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]]; // Vincenzo Librandi, Feb 09 2012
(PARI) for(n=1, 40, print1(900*n + 1", ")); \\ Vincenzo Librandi, Feb 09 2012
CROSSREFS
Cf. A158406.
Sequence in context: A093218 A093215 A252674 * A250782 A031738 A268585
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 18 2009
STATUS
approved