A106129 Numbers k such that the k-th semiprime == 4 (mod k).

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

Offset

1,2

Comments

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

a(28) <= 121769718289846, a(29) <= 121769718289883 and a(38) <= 121769718292241. - Martin Ehrenstein, Oct 28 2022

Links

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

Lucas A. Brown, semiprimemods.py

Example

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

Crossrefs

Cf. A001358, A357808.

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