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arXiv · 1812.01109

Ramanujan's theta functions and linear combinations of four triangular numbers

Zhi-Hong Sun
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Abstract

Let $\Bbb Z$ and $\Bbb Z^+$ be the set of integers and the set of positive integers, respectively. For $a,b,c,d,n\in\Bbb Z^+$ let $t(a,b,c,d;n)$ be the number of representations of $n$ by $ax(x+1)/2+by(y+1)/2+cz(z+1)/2+dw(w+1)/2$ $(x,y,z,w\in\Bbb Z)$. In this paper, by using Ramanujan's theta functions $\varphi(q)$ and $\psi(q)$ we present many formulas and conjectures on $t(a,b,c,d;n)$.

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Zhi-Hong Sun. 2018-11-27. Ramanujan's theta functions and linear combinations of four triangular numbers. https://arxiv.org/abs/1812.01109

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