A201920 a(n) = 2^n mod 125.
1, 2, 4, 8, 16, 32, 64, 3, 6, 12, 24, 48, 96, 67, 9, 18, 36, 72, 19, 38, 76, 27, 54, 108, 91, 57, 114, 103, 81, 37, 74, 23, 46, 92, 59, 118, 111, 97, 69, 13, 26, 52, 104, 83, 41, 82, 39, 78, 31, 62, 124, 123, 121, 117, 109, 93, 61, 122, 119, 113, 101, 77, 29
Offset: 0
Examples
a(7) = 2^7 mod 125 = 3.
Links
- G. C. Greubel, Table of n, a(n) for n = 0..10000
- Index entries for linear recurrences with constant coefficients, signature (1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1).
Programs
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GAP
a:=List([0..100],n->PowerMod(2,n,125));; Print(a); # Muniru A Asiru, Jan 27 2019
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Magma
[Modexp(2, n, 125): n in [0..120]]; // G. C. Greubel, Oct 17 2018
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Mathematica
PowerMod[2,Range[0,100],125] (* Harvey P. Dale, Aug 12 2013 *)
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PARI
a(n)=lift(Mod(2,125)^n) \\ Charles R Greathouse IV, Mar 22 2016
Formula
For n > 50: a(n) = a(n-1) - a(n-50) + a(n-51).
G.f.: (1 + x + 2x^2 + 4x^3 + 8x^4 + 16x^5 + 32x^6 - 61x^7 + 3x^8 + 6x^9 + 12x^10 + 24x^11 + 48x^12 - 29x^13 - 58x^14 + 9x^15 + 18x^16 + 36x^17 - 53x^18 + 19x^19 + 38x^20 - 49x^21 + 27x^22 + 54x^23 - 17x^24 - 34x^25 + 57x^26 - 11x^27 - 22x^28 - 44x^29 + 37x^30 - 51x^31 + 23x^32 + 46x^33 - 33x^34 + 59x^35 - 7x^36 - 14x^37 - 28x^38 - 56x^39 + 13x^40 + 26x^41 + 52x^42 - 21x^43 - 42x^44 + 41x^45 - 43x^46 + 39x^47 - 47x^48 + 31x^49 + 63x^50) / ((1-x)*(1+x^2)*(1 - x^2 + x^4 - x^6 + x^8 - x^10 + x^12 - x^14 + x^16 - x^18 + x^20 - x^22 + x^24 - x^26 + x^28 - x^30 + x^32 - x^34 + x^36 - x^38 + x^40 - x^42 + x^44 - x^46 + x^48)).
Periodic with period 100.