A115020 Count backwards from 100 in steps of 7.

100, 93, 86, 79, 72, 65, 58, 51, 44, 37, 30, 23, 16, 9, 2

Offset

0,1

Comments

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. Most patients would stop when they get to 2, but 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

References

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

Links

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

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

Tanya Khovanova, Non Recursions

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

Wikipedia, Serial sevens

Formula

a(n) = 100 - 7n.

Mathematica

Range[100, 2, -7] (* Harvey P. Dale, Apr 11 2014 *)

Prog

(PARI) a(n)=100-7*n \\ Charles R Greathouse IV, Feb 25 2019
(Scala) (0 to 14).map(100 - 7 * _) // Alonso del Arte, May 09 2019

Crossrefs

First fifteen terms of A017005 backwards.

Sequence in context: A242615 A090292 A020993 * A169735 A096582 A308660

Adjacent sequences: A115017 A115018 A115019 * A115021 A115022 A115023

Keyword

easy,fini,full,nonn

Author

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

Status

approved