STATUS
editing
approved
The OEIS is supported by the many generous donors to the OEIS Foundation.
editing
approved
#[[3]]-#[[1]]&/@Partition[Range[0, 20]!, 3, 1] (* Harvey P. Dale, Aug 10 2023 *)
approved
editing
reviewed
approved
proposed
reviewed
editing
proposed
For n >= 3, a(n) = number whose factorial base representation (A007623) begins with digits {n-1} and {n-2} followed by n-3 zeros. Viewed in that base, this sequence looks like this: 1, 21, 320, 4300, 54000, 650000, 7600000, 87000000, 980000000, A900000000, BA000000000, ... (where "digits" A and B stand for placeholder values 10 and 11 respectively). - Antti Karttunen, May 07 2015.
The Formula Described for the sequence is expressed by a(n) = n! - (n-2)!. The values for the same if, n = 2 the term thus obtained is 1. Also for values of n as 3 and 4 the terms are 5 and 22 respectively. But the terms respective terms seen in the series occupies term number 0, 1 and 2 (if count from 0) or term number 1, 2 and 3 (if taken from 1). The value of n taken in the formula gives terms which are of preceding or succeeding term numbers.
So, according to my observation in sequence of Factorials and refereed sequences A000142, A001563 the formula according to me can be a(n) = (n+2)!-n!.
proposed
editing
editing
proposed
editing
proposed
The Formula Described for the sequence is expressed by a(n) = n! - (n-2)!. The values for the same if, n = 2 the term thus obtained is 1. Also for values of n as 3 and 4 the terms are 5 and 22 respectively. But the terms respective terms seen in the series occupies term number 0, 1 and 2 (if count from 0) or term number 1, 2 and 3 (if taken from 1). The value of n taken in the formula gives terms which are of preceding or succeeding term numbers.
So, according to my observation in sequence of Factorials and refereed sequences AOOO142, A001563 the formula according to me can be a(n) = (n+2)!-n!.
approved
editing