The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A005347 First differences of A005579. (Formerly M0690) 29
 1, 1, 2, 3, 5, 8, 13, 20, 34, 53, 88, 143, 236, 387, 641, 1061, 1763, 2937, 4903, 8202, 13750, 23095, 38850, 65461, 110465, 186665, 315827, 535011, 907341, 1540416, 2617782, 4452846, 7581016, 12917486, 22027745, 37591270, 64196610 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS This is example 42 in Guy's paper. The first seven terms are the same as the Fibonacci sequence A000045. Subsequent terms deviate from Fibonacci. - T. D. Noe, May 08 2006 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS R. K. Guy, Letter to N. J. A. Sloane, 1988-04-12 (annotated scanned copy) R. K. Guy, Letters to N. J. A. Sloane, 1986-88 R. K. Guy, The Second Strong Law of Small Numbers, Math. Mag, 63 (1990), no. 1, 3-20. R. K. Guy, The Second Strong Law of Small Numbers, Math. Mag, 63 (1990), no. 1, 3-20. [Annotated scanned copy] Richard Laatsch, Measuring the abundancy of integers, Mathematics Magazine 59 (2) (1986) 84-92. FORMULA a(n) = A005579(n+1) - A005579(n) - T. D. Noe, May 08 2006 MATHEMATICA prod = Interval[1]; k = k0 = 0; Table[While[Max[prod] <= n, k++; p = Prime[k]; prod = N[prod*p/(p - 1), 30]]; If[Min[prod] > n, If[k > 2, Print[k - k0] ]; k0 = k; k, "too few digits"], {n, 2, 39}] // Differences (* Jean-François Alcover, Oct 07 2016, using T. D. Noe's code for A005579 *) CROSSREFS Cf. A005579 (least number of distinct prime factors in even numbers having an abundancy index >n). Sequence in context: A080106 A293644 A158415 * A100582 A193616 A273715 Adjacent sequences:  A005344 A005345 A005346 * A005348 A005349 A005350 KEYWORD nonn,nice AUTHOR N. J. A. Sloane, R. K. Guy, Apr 12 1988 EXTENSIONS More terms from Harvey P. Dale, Aug 07 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 22 15:13 EST 2022. Contains 350481 sequences. (Running on oeis4.)