[1]k=1,m=4
1/4・{2^n+(2cosπ/4)^ncos(n-2)π/4+(2cos3π/4)^ncos3(n-2)π/4}
cosnπ/4+(-1)^ncos3nπ/4
は,n-2が偶数のとき
=-2cosnπ/2・cosnπ/4
n-2=4mのとき,-2cosmπ
n-2=4m+2のとき,2cos(m+1/2)π=-2sinmπ
n-2が奇数のとき
=-2sinnπ/2・sinnπ/4
n-2=4m+1のとき,-2sin(m+1/4)π
n-2=4m+3のとき,2sin(m+3/4)π=2cos(m+1/4)π
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[2]k=2,m=4
1/4・{2^n+(2cosπ/4)^ncos(n-4)π/4+(2cos3π/4)^ncos3(n-4)π/4}
cosnπ/4+(-1)^ncos3nπ/4
は,n-4が偶数のとき
=-2cosnπ/2・cosnπ/4
n-4=4mのとき,-2cosmπ
n-4=4m+2のとき,2cos(m+1/2)π=-2sinmπ
n-4が奇数のとき
=-2sinnπ/2・sinnπ/4
n-4=4m+1のとき,-2sin(m+1/4)π
n-4=4m+3のとき,2sin(m+3/4)π=2cos(m+1/4)π
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[3]k=3,m=4
1/4・{2^n+(2cosπ/4)^ncos(n-6)π/4+(2cos3π/4)^ncos3(n-6)π/4}
cosnπ/4+(-1)^ncos3nπ/4
は,n-6が偶数のとき
=-2cosnπ/2・cosnπ/4
n-6=4mのとき,-2cosmπ
n-6=4m+2のとき,2cos(m+1/2)π=-2sinmπ
n-4が奇数のとき
=-2sinnπ/2・sinnπ/4
n-6=4m+1のとき,-2sin(m+1/4)π
n-6=4m+3のとき,2sin(m+3/4)π=2cos(m+1/4)π
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