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A106131 Numbers k such that the k-th semiprime == 6 (mod k). 1
1, 2, 3, 4, 8, 10, 57, 59, 69, 6914, 613376, 613403, 613431, 613432, 613436, 613447, 613453, 613483, 613484, 613507, 613511, 613513, 613516, 613531, 613535, 613541, 613547, 613579, 613580, 613597, 613607, 6384425453, 6384425504, 6384425519, 6384425555 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(42) > 10^12. - Lucas A. Brown, Oct 19 2020

LINKS

Lucas A. Brown, Table of n, a(n) for n = 1..41

EXAMPLE

a(5) = 8 is a term because the 8th semiprime is 22 and 22 == 6 (mod 8).

MATHEMATICA

Module[{sp=Select[Range[10^7], PrimeOmega[#]==2&]}, Flatten[ Position[ Thread[ {sp, Range[ Length[sp]]}], _?(Mod[#[[1]], #[[2]]]==6&), {1}, Heads-> False]]] (* Harvey P. Dale, May 09 2015 *)

CROSSREFS

Cf. A001358.

Sequence in context: A207644 A114854 A127279 * A275646 A279194 A050727

Adjacent sequences:  A106128 A106129 A106130 * A106132 A106133 A106134

KEYWORD

hard,nonn

AUTHOR

Shyam Sunder Gupta, May 07 2005

EXTENSIONS

a(1)-a(4) and a(32)-a(41) by Lucas A. Brown, Oct 19 2020

STATUS

approved

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Last modified November 28 01:24 EST 2021. Contains 349396 sequences. (Running on oeis4.)