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A084926 Inverse hyperbolic cotangent reducible numbers. The hyperbolic analog of the non-Stormer numbers (A002312). 2
5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 26, 27, 29, 31, 33, 34, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 56, 57, 59, 61, 63, 64, 65, 67, 69, 71, 73, 75, 76, 77, 79, 81, 83, 85, 86, 87, 89, 91, 93, 94, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 116, 117, 118 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

n is in the sequence if y=(xn+1)/(x+n) is an integer for some integer x where 1<x<n.

LINKS

Table of n, a(n) for n=1..66.

PROG

(PARI) for(n=1, 120, x=1; b=0; while(x<n, x=x+1; r=(x+n)*floor((x*n+1)/(x+n)); if(r>=(x*n+1), b=b+1)); if(b>0, print1(n, ", ")))

CROSSREFS

Cf. A002312 (non-Stormer numbers), A084925 (arccoth irreducible).

Sequence in context: A097985 A099047 A174392 * A049013 A267872 A062545

Adjacent sequences:  A084923 A084924 A084925 * A084927 A084928 A084929

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jun 12 2003

STATUS

approved

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Last modified January 26 16:58 EST 2020. Contains 331280 sequences. (Running on oeis4.)