A097715 Decimal expansion of 7*sqrt(3)/2.

6, 0, 6, 2, 1, 7, 7, 8, 2, 6, 4, 9, 1, 0, 7, 0, 5, 2, 7, 3, 4, 6, 0, 6, 2, 1, 9, 5, 2, 7, 0, 5, 5, 3, 2, 8, 4, 2, 9, 9, 8, 1, 8, 3, 8, 8, 3, 3, 6, 3, 3, 2, 1, 9, 8, 1, 9, 5, 3, 2, 4, 4, 2, 8, 0, 8, 1, 7, 6, 5, 5, 5, 9, 1, 8, 0, 8, 0, 0, 1, 2, 9, 7, 8, 4, 0, 1, 1, 6, 5, 3, 6, 5, 0, 3, 7, 0, 0, 1, 4, 8, 6, 4, 6, 9

Offset

1,1

Comments

Corresponds to the minimal height-to-diameter ratio of a cylinder such that seven of them may be placed in mutual contact.

Also the surface area of a triaugmented triangular prism (Johnson solid J_51) with unit edge. - Paolo Xausa, Jul 01 2025

References

Martin Gardner, The Scientific American book of Mathematical Puzzles & Diversions, pp. 115 Simon & Shuster NY 1959 (or Hexaflexagons And Other Mathematical Diversions, The Univ. of Chicago Press Chicago IL 1988).

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Wikipedia, Triaugmented triangular prism.

Index entries for algebraic numbers, degree 2

Example

6.0621778264910705273460621952705532842998183883363...

Mathematica

RealDigits[7Sqrt[3]/2, 10, 105][[1]]

Prog

(PARI) sqrt(147)/2 \\ Charles R Greathouse IV, Apr 05 2026

Crossrefs

Cf. A002194, A385506.

Sequence in context: A280692 A161419 A136526 * A316710 A198499 A092605

Adjacent sequences: A097712 A097713 A097714 * A097716 A097717 A097718

Keyword

nonn,easy,cons

Author

Lekraj Beedassy, Sep 21 2004

Extensions

Corrected and extended by Rick L. Shepherd and Ray Chandler, Sep 21 2004

Status

approved