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A039670 Sets of 4 numbers in arithmetic progression with common difference 6 and whose phi values are equal. 1
72, 78, 84, 90, 216, 222, 228, 234, 76326, 76332, 76338, 76344, 101526, 101532, 101538, 101544, 116646, 116652, 116658, 116664, 146886, 146892, 146898, 146904, 298086, 298092, 298098, 298104, 369366, 369372, 369378, 369384, 624966, 624972 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This is really four sequences, not one! A050498 is a better version. - N. J. A. Sloane, Jan 01 2005

REFERENCES

D. Wells, Curious and interesting numbers, Penguin Books, p. 112 (but beware errors).

LINKS

Table of n, a(n) for n=1..34.

MAPLE

with(numtheory):for n from 1 to 1000000 do if(phi(n)=phi(n+6) and phi(n+6)=phi(n+12) and phi(n+12)=phi(n+18)) then printf("%d, %d, %d, %d, ", n, n+6, n+12, n+18) fi od: # C. Ronaldo

CROSSREFS

Sequence in context: A181466 A243541 A138691 * A065147 A214226 A043187

Adjacent sequences:  A039667 A039668 A039669 * A039671 A039672 A039673

KEYWORD

nonn

AUTHOR

Felice Russo

EXTENSIONS

Corrected by Jud McCranie, Dec 26 1999

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 29 2004

STATUS

approved

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Last modified April 11 14:58 EDT 2021. Contains 342886 sequences. (Running on oeis4.)