This site is supported by donations to The OEIS Foundation.



(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A115020 Count backwards from 100 in steps of 7. 1
100, 93, 86, 79, 72, 65, 58, 51, 44, 37, 30, 23, 16, 9, 2 (list; graph; refs; listen; history; text; internal format)



Sometimes used to gauge the concentration ability of a patient with Alzheimer's disease. The combination of a simple arithmetic operation with an unusual decrement forces the patient to rely on short term memory for the computation. Theoretically, most patients will stop when they get to 2, the psychiatrist might be satisfied with the first five or so terms. In this capacity the sequence is mentioned a few times in the movie "Safe House" (1998) in which Mace Sowell (Patrick Stewart) tries to memorize the sequence and is asked it by the psychiatrist (Hector Elizondo). In real life, other decrements can be used; Fish (1996) suggests 3 and 4.

In the next-to-last episode of "Boston Legal," Denny Crane (William Shatner) is asked this sequence by a doctor while in an MRI machine. He gets confused at 86, following it with 81. (Both Shatner and Stewart have played captain of the Enterprise on TV.) - Wilfredo Lopez (chakotay147138274(AT)yahoo.com), Dec 03 2008


S. Fish, "Alzheimer's: Caring for Your Loved One, Caring for Yourself", Wheaton, Illinois: Harold Shaw Publishers, 1996, p. 34

Max Hayman, Two minute clinical test for measurement of intellectual impairment in psychiatric disorders, Arch. Neurpsych. 47:3 (1942), pp. 454-464.

Robert Thomas Manning, The serial sevens test, Arch Intern Med. 142:6 (1982), p. 1192.


Table of n, a(n) for n=0..14.

Intelihealth, Dementia: Overview: Diagnosis.

Tanya Khovanova, Non Recursions

Wikipedia, Serial sevens


a(n) = 100 - 7n.


Range[100, 1, -7] (* Harvey P. Dale, Apr 11 2014 *)


First fifteen terms of A017005 backwards.

Sequence in context: A242615 A090292 A020993 * A169735 A096582 A220023

Adjacent sequences:  A115017 A115018 A115019 * A115021 A115022 A115023




Robert Happelberg (roberthappelberg(AT)yahoo.com), Feb 23 2006



Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified September 25 18:20 EDT 2017. Contains 292499 sequences.