A036928 Composite numbers whose prime factors contain no digits other than 0 and 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

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 A357169 A254970

Adjacent sequences: A036925 A036926 A036927 * A036929 A036930 A036931

Keyword

nonn,base

Author

Patrick De Geest, Jan 04 1999

Extensions

Description clarified by Ray Chandler, Nov 07 2008

Status

approved