The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A308899 a(n) = largest prime factor of the number with decimal expansion 20305070...0p_n where p_n = n-th prime. 1
 2, 29, 131, 33287, 17627, 1754975809, 59218567, 318879703697, 2030507011013017019023, 14400758943354730631369, 1016015647, 32002443156997, 2464082401591041689, 4916481866859605372937116297910511, 2030507011013017019023029031037041043047 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The Honaker-Caldwell link gives a(25) = 20305070110130170190230290310370410430470530590 \61067071073079083089097, with 70 digits. LINKS Daniel Suteu, Table of n, a(n) for n = 1..43 G. L. Honaker, Jr. and Chris Caldwell, Prime Curios!, 2030507...[70 digits]...89097. EXAMPLE Here are Maple's factorizations of 2, 203, 20305, ... (the factors appear in random order): 2 = (2) 203 = (7) (29) 20305 = (5) (31) (131) 2030507 = (61) (33287) 2030507011 = (13) (17627) (8861) 2030507011013 = (13) (89) (1754975809) 2030507011013017 = (59218567) (34288351) 2030507011013017019 = (7) (547) (1663) (318879703697) MATHEMATICA Table[FactorInteger[FromDigits[Flatten[IntegerDigits/@Riffle[Prime[Range[n]], 0]]]][[-1, 1]], {n, 20}] (* Harvey P. Dale, May 09 2021 *) PROG (PARI) pp = 0; forprime (p=2, 47, print1 (vecmax(factor(pp = pp * 10^(1+#digits(p)) + p)[, 1]~) ", ")) \\ Rémy Sigrist, Jul 13 2019 CROSSREFS Inspired by the comment in Bernard Schott's A309101. Sequence in context: A123004 A062618 A128842 * A028883 A024200 A137625 Adjacent sequences: A308896 A308897 A308898 * A308900 A308901 A308902 KEYWORD nonn,base AUTHOR N. J. A. Sloane, Jul 13 2019 EXTENSIONS More terms from Rémy Sigrist, Jul 13 2019 STATUS approved

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

Last modified May 25 01:50 EDT 2024. Contains 372782 sequences. (Running on oeis4.)