A045800 0-ish numbers (end in 01, 07, 43, 49).
1, 7, 43, 49, 101, 107, 143, 149, 201, 207, 243, 249, 301, 307, 343, 349, 401, 407, 443, 449, 501, 507, 543, 549, 601, 607, 643, 649, 701, 707, 743, 749, 801, 807, 843, 849, 901, 907, 943, 949, 1001, 1007, 1043, 1049, 1101, 1107, 1143, 1149, 1201, 1207
Offset: 1
Links
- Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
- Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).
Programs
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Haskell
import Data.List (findIndices) a045800 n = a045800_list !! (n-1) a045800_list = findIndices (`elem` [1,7,43,49]) $ cycle [0..99] -- Reinhard Zumkeller, Jan 23 2012
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Mathematica
LinearRecurrence[{1,0,0,1,-1},{1,7,43,49,101},60] (* Harvey P. Dale, Jul 26 2015 *)
Formula
G.f.: x*(1+6*x+36*x^2+6*x^3+51*x^4)/(1-x-x^4+x^5). - Colin Barker, Jan 23 2012
a(n) = (50*n-8*i^(n*(n+1))-19*(-1)^n-75)/2, where i=sqrt(-1). - Bruno Berselli, Feb 22 2012
Extensions
More terms from Erich Friedman.