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A036928 Composite numbers whose prime factors contain no digits other than 0 and 1. 1
121, 1111, 1331, 10201, 12221, 14641, 111221, 112211, 134431, 161051, 1021211, 1030301, 1112221, 1223431, 1234321, 1478741, 1771561, 10212211, 11121011, 11233321, 11333311, 12101111, 12234431, 13457741, 13577531, 16266151 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..26.

Index entries for sequences related to prime factors.

FORMULA

Sum_{n>=1} 1/a(n) = Product_{p in A020449} (p/(p - 1)) - Sum_{p in A020449} 1/p - 1 = 0.0102023428... . - Amiram Eldar, May 18 2022

CROSSREFS

Cf. A020449, A036302-A036325, A036929.

Sequence in context: A307858 A329100 A208261 * A088171 A254970 A036308

Adjacent sequences:  A036925 A036926 A036927 * A036929 A036930 A036931

KEYWORD

nonn,base,changed

AUTHOR

Patrick De Geest, Jan 04 1999

EXTENSIONS

Description clarified by Ray Chandler, Nov 07 2008

STATUS

approved

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Last modified May 28 16:37 EDT 2022. Contains 354119 sequences. (Running on oeis4.)