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 A002015 a(n) = n^2 reduced mod 100. 4
 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 0, 21, 44, 69, 96, 25, 56, 89, 24, 61, 0, 41, 84, 29, 76, 25, 76, 29, 84, 41, 0, 61, 24, 89, 56, 25, 96, 69, 44, 21, 0, 81, 64, 49, 36, 25, 16, 9, 4, 1, 0, 1, 4, 9, 16, 25, 36, 49, 64, 81 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Periodic with period 50: (0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 0, 21, 44, 69, 96, 25, 56, 89, 24, 61, 0, 41, 84, 29, 76, 25, 76, 29, 84, 41, 0, 61, 24, 89, 56, 25, 96, 69, 44, 21, 0, 81, 64, 49, 36, 25, 16, 9, 4, 1) and next term is 0. The period is symmetrical about the "midpoint" 25. - Zak Seidov, Oct 26 2009 Contribution from Reinhard Zumkeller, Mar 21 2010: (Start) a(n) = A174452(n) mod 100; A008959(n) = a(n) mod 10; a(m*n) = a(m)*a(n) mod 100; a(n) = (n mod 100)^2 mod 100; A010461 gives the range of this sequence; a(n) = n for n = 0, 1, and 25. (End) LINKS Index entries for linear recurrences with constant coefficients, signature (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, 0, 1). FORMULA a(n) = (n mod 10) * ((n mod 10) + 20 * ((n\10) mod 10)) mod 100. - Reinhard Zumkeller, Mar 21 2010 MATHEMATICA PowerMod[Range[0, 60], 2, 100] (* Harvey P. Dale, Nov 28 2012 *) PROG (PARI) a(n)=n^2%100 \\ Charles R Greathouse IV, Oct 07 2015 CROSSREFS Cf. A053879, A070430, A070431, A070432, A070433, A070434, A070435, A070438, A070442, A070452, A159852. Sequence in context: A066308 A063462 A098736 * A257587 A257588 A303269 Adjacent sequences:  A002012 A002013 A002014 * A002016 A002017 A002018 KEYWORD nonn,easy AUTHOR EXTENSIONS Definition rephrased at the suggestion of Zak Seidov, Oct 26 2009 STATUS approved

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Last modified January 20 23:29 EST 2020. Contains 331104 sequences. (Running on oeis4.)