Paydarpay, yake az mafhumhoi asosii matematika ast. Paydarpay az elementhoi tabiatashon gunogun, ki bo adadhoi naturali 1, 2 … p, numera- siyashuda tashkil meyobad va ba namudi l,, l2, •••» khp 6 mukhtasar (lp) navishta meshavad. Elementhoe, ki az onho’ Paydarpay tartib doda meshavad, uzvhoi Paydarpay nom dorand. Odatan Paydarpay dar surati doda shudani uzvi p-um yo muvofiqi formulai rekurrentie muayyan karda meshavad, ki zimni on har yak uzvi minbadaro ba vositai uzvi peshina muayyan kardan mumkin ast. Paydarpaihoi adadi va funksionali beshtar mamuland (uzvhoi onho muvofiqan adad va funksiya meboshand).
Agar elementhoi Paydarpai adadi dar mavridi kofi kalon budani nomerhoi p az adadi a har qadar kam farq kunand, on goh Paydarpairo nazdikshav anda va adadi a-ro khududi on menomand (hududi Paydarpaii funksionali niz hamin tavr muayyan karda meshavad). Masalan, Paydarpaii (2) va (4) naz- dikshavandaandu adadi 0 va funksiyai V (! + *•) muvofiqan hududhoi onho meboshand. Paydarpaihoi nazdiknashavanda, masalan, Paydarpaii (1) va (3) dursh a v a n d a nomida meshavand.