Möbius Practice — LCM Sums, Divisor-Count, Omega Numbers
Practice problems for Möbius inversion: LCMSUM, two-variable lcm sum (O(n^3/4)), FSF’s game with offline difference, divisor-count sum d(ij), Omega Numbers with Dirichlet suffix sum.
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3 posts
Möbius Techniques
Seven core techniques for Möbius inversion problems: loop shortening, gcd indicator expansion, coprimality reduction, Dirichlet convolution via T=dk, divisor symmetry, diagonal symmetry, and value-domain cnt[] tricks.
Multiplicative Functions, Möbius Inversion & Dirichlet Convolution
Multiplicative functions, single-point and linear-sieve evaluation; Möbius function, both forms of Möbius inversion with full derivations and examples; Dirichlet convolution, key identities, Du Jiao sieve; generalized Möbius …