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 A105620 Matrix inverse square-root of triangle A105615. 5
 1, -1, 1, -2, -2, 1, -10, -4, -3, 1, -74, -20, -7, -4, 1, -706, -148, -39, -11, -5, 1, -8162, -1412, -315, -70, -16, -6, 1, -110410, -16324, -3243, -635, -116, -22, -7, 1, -1708394, -220820, -40167, -7264, -1183, -180, -29, -8, 1, -29752066, -3416788, -579159, -99191, -15065, -2049, -265, -37, -9, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS Column 0 is negative A000698 (related to double factorials). Column 1 equals twice column 0 after the initial term. LINKS EXAMPLE Triangle begins: 1; -1,1; -2,-2,1; -10,-4,-3,1; -74,-20,-7,-4,1; -706,-148,-39,-11,-5,1; -8162,-1412,-315,-70,-16,-6,1; -110410,-16324,-3243,-635,-116,-22,-7,1; -1708394,-220820,-40167,-7264,-1183,-180,-29,-8,1; -29752066,-3416788,-579159,-99191,-15065,-2049,-265,-37,-9,1; ... PROG (PARI) T(n, k)=local(R, M=matrix(n+1, n+1, m, j, if(m>=j, if(m==j, 1, if(m==j+1, -2*j, polcoeff(1/sum(i=0, m-j, (2*i)!/i!/2^i*x^i)+O(x^m), m-j)))))); R=(M+M^0)/2; for(i=1, floor(2*log(n+2)), R=(R+M*R^(-1))/2); return(if(n

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Last modified January 18 13:38 EST 2022. Contains 350455 sequences. (Running on oeis4.)