In number theory, a factoriangular number is an integer formed by adding a factorial and a triangular number with the same index. The name is a portmanteau of "factorial" and "triangular." == Definition == For n ≥ 1 {\displaystyle n\geq 1} , the n {\displaystyle n} th factoriangular number, denoted Ft n {\displaystyle \operatorname {Ft} _{n}} , is defined as the sum of the n {\displaystyle n} th factorial and the n {\displaystyle n} th triangular number: Ft n = n !
In number theory, a factoriangular number is an integer formed by adding a factorial and a triangular number with the same index. The name is a portmanteau of "factorial" and "triangular." == Definition == For n ≥ 1 {\displaystyle n\geq 1} , the n {\displaystyle n} th factoriangular number, denoted Ft n {\displaystyle \operatorname {Ft} _{n}} , is defined as the sum of the n {\displaystyle n} th factorial and the n {\displaystyle n} th triangular number: Ft n = n !
Source: Wikipedia "Factoriangular number" · CC BY-SA 4.0
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