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A092242 Numbers that are congruent to {5, 7} mod 12. 2
5, 7, 17, 19, 29, 31, 41, 43, 53, 55, 65, 67, 77, 79, 89, 91, 101, 103, 113, 115, 125, 127, 137, 139, 149, 151, 161, 163, 173, 175, 185, 187, 197, 199, 209, 211, 221, 223, 233, 235, 245, 247, 257, 259, 269, 271, 281, 283, 293, 295, 305, 307, 317, 319, 329, 331 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

L. B. W. Jolley, "Summation of Series", Dover Publications, 1961, p. 64.

LINKS

Table of n, a(n) for n=1..56.

Index entries for linear recurrences with constant coefficients, signature (1,1,-1).

FORMULA

1/5^2 + 1/7^2 + 1/17^2 + 1/19^2 + 1/29^2 + 1/31^2...= (Pi^2*(2 - sqrt(3))/36 = 0.073459792... [Jolley] - Gary W. Adamson, Dec 20 2006

a(n) = 12*n - a(n-1) - 12 (with a(1)=5). - Vincenzo Librandi, Nov 16 2010

From R. J. Mathar, Oct 08 2011: (Start)

a(n) = 6*n - 3 - 2*(-1)^n.

G.f.: x*(5+2*x+5*x^2) / ( (1+x)*(x-1)^2 ). (End)

CROSSREFS

Fifth row of A092260.

Sequence in context: A099389 A099382 A163633 * A003630 A122565 A247607

Adjacent sequences:  A092239 A092240 A092241 * A092243 A092244 A092245

KEYWORD

nonn

AUTHOR

Giovanni Teofilatto, Feb 19 2004

EXTENSIONS

Edited and extended by Ray Chandler, Feb 21 2004

STATUS

approved

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Last modified January 23 21:55 EST 2021. Contains 340386 sequences. (Running on oeis4.)