login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A106129 Numbers k such that the k-th semiprime == 4 (mod k). 0
1, 2, 5, 37, 38, 58, 61, 70, 77, 613379, 613413, 613415, 613429, 613485, 613509, 613518, 613521, 613533, 613543, 613599, 6384425449, 6384425459, 6384425463, 6384425517, 6384425557, 6384425574, 6384425634 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(28) > 10^12. - Lucas A. Brown, Oct 18 2020

LINKS

Table of n, a(n) for n=1..27.

EXAMPLE

a(3) = 5 is a term because the 5th semiprime is 14 and 14 == 4 (mod 5).

CROSSREFS

Cf. A001358.

Sequence in context: A111491 A331402 A284605 * A163499 A086218 A202637

Adjacent sequences:  A106126 A106127 A106128 * A106130 A106131 A106132

KEYWORD

hard,more,nonn

AUTHOR

Shyam Sunder Gupta, May 07 2005

EXTENSIONS

a(21)-a(27) by Lucas A. Brown, Oct 18 2020

a(1), a(2) by Lucas A. Brown, Oct 19 2020

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 18 06:50 EDT 2021. Contains 348066 sequences. (Running on oeis4.)