2107560

Appears in sequences

• a(n) = 4*a(n-1) - a(n-2) with a(0) = 0, a(1) = 1.at n=12A001353
• a(n) = 4*a(n-2) - a(n-4) for n > 1, a(n) = n for n = 0, 1.at n=24A002530
• Pisot sequence E(4,15): a(n) = floor(a(n-1)^2/a(n-2)+1/2) for n>1, a(0)=4, a(1)=15.at n=10A010905
• Theta series of D*_26 lattice.at n=10A022079
• Expansion of (1 + x + x^2)/(1 - 4x^2 + x^4).at n=23A108412
• Interleave denominators and numerators of convergents to sqrt(3).at n=34A140827
• Numerators b(n) of Pythagorean approximations b(n)/a(n) to sqrt(3).at n=10A195503
• List of triples (r,s,t): the matrix M = [[4,12,9][2,7,6][1,4,4]] is raised to successive powers, then (r,s,t) are the square roots of M[3,1], M[1,1], M[1,3] respectively.at n=36A249578
• Denominators of the other-side convergents to sqrt(3).at n=22A259592
• Triangle read by rows: T(n,k) is the number of words over alphabet {0,1,2,3} having exactly k occurrences of the string 01, where n>=0 and k>=0.at n=36A261711
• p-INVERT of the positive integers, where p(S) = 1 - 4*S^2.at n=11A290908
• Expansion of (1 - x)^4/((1 - x)^6 + x^6).at n=23A307089
• a(n) = (4/15)*n*(n - 1)*(n^3 - 9*n^2 + 26*n - 9).at n=26A319576