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 A262389 Numbers whose last digit is composite. 3
 4, 6, 8, 9, 14, 16, 18, 19, 24, 26, 28, 29, 34, 36, 38, 39, 44, 46, 48, 49, 54, 56, 58, 59, 64, 66, 68, 69, 74, 76, 78, 79, 84, 86, 88, 89, 94, 96, 98, 99, 104, 106, 108, 109, 114, 116, 118, 119, 124, 126, 128, 129, 134, 136, 138, 139, 144, 146, 148, 149 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers ending in 4, 6, 8 or 9. Union of A017317, A017341, A017365 and A017377. Subsequence of A118951 (numbers containing at least one composite digit). Complement of (A197652 Union A260181). LINKS Gerald Hillier, Didier Lachieze, Last Digit Composite Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1). FORMULA G.f.: x*(4+2*x+2*x^2+x^3+x^4)/((x-1)^2*(1+x+x^2+x^3)). a(n) = a(n-1) + a(n-4) - a(n-5) for n>5. a(n) = (5*n+1-(-1)^n+(3+(-1)^n)*(-1)^((2*n-3-(-1)^n)/4)/2)/2. MAPLE A262389:=n->(5*n+1-(-1)^n+(3+(-1)^n)*(-1)^((2*n-3-(-1)^n)/4)/2)/2: seq(A262389(n), n=1..100); MATHEMATICA Table[(5n+1-(-1)^n+(3+(-1)^n)*(-1)^((2n-3-(-1)^n)/4)/2)/2, {n, 100}] LinearRecurrence[{1, 0, 0, 1, -1}, {4, 6, 8, 9, 14}, 80] (* Vincenzo Librandi, Sep 21 2015 *) CoefficientList[Series[(4 + 2*x + 2*x^2 + x^3 + x^4)/((x - 1)^2*(1 + x + x^2 + x^3)), {x, 0, 80}], x] (* Wesley Ivan Hurt, Sep 21 2015 *) Select[Range[200], CompositeQ[Mod[#, 10]]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 21 2019 *) PROG (MAGMA) [(5*n+1-(-1)^n+(3+(-1)^n)*(-1)^((2*n-3-(-1)^n) div 4) div 2) div 2: n in [1..70]]; // Vincenzo Librandi, Sep 21 2015 CROSSREFS Cf. A017317, A017341, A017365, A017377. Cf. A118951, A197652, A260181 (last digit is prime). Sequence in context: A119492 A285586 A118951 * A254755 A275624 A228019 Adjacent sequences:  A262386 A262387 A262388 * A262390 A262391 A262392 KEYWORD nonn,base,easy,changed AUTHOR Wesley Ivan Hurt, Sep 21 2015 EXTENSIONS Name edited by Jon E. Schoenfield, Feb 15 2018 STATUS approved

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Last modified January 22 15:57 EST 2019. Contains 319364 sequences. (Running on oeis4.)