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   JordiGH (jordigh@mathstodon.xyz)'s status on Wednesday, 15-Nov-2023 00:15:50 JST JordiGH

   Where did the i, j, k notation for indices begin?

   My earliest clue is that it probably started when we started indexing our summations. Euler :euler: used ∑ for sums, but he didn't use indices. Fourier in 1823 did use indices. Was there someone between Euler and Fourier who also used indices in their summations?