The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A355600 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A355600

a(1) = 37. For n > 1, a(n) = smallest prime q such that q^(a(n-1)-1) == 1 (mod a(n-1)^2).
(history; published version)

#4 by N. J. A. Sloane at Sat Jul 16 01:31:35 EDT 2022

STATUS

proposed

approved

#3 by Felix Fröhlich at Sat Jul 09 04:24:43 EDT 2022

STATUS

editing

proposed

#2 by Felix Fröhlich at Sat Jul 09 04:15:52 EDT 2022

NAME

allocated for Felix Fröhlich

a(1) = 37. For n > 1, a(n) = smallest prime q such that q^(a(n-1)-1) == 1 (mod a(n-1)^2).

DATA

37, 691, 19181, 5849, 18503, 37853, 478741, 18401827, 571007279, 5860639859

OFFSET

1,1

COMMENTS

Is this overall an increasing sequence or does it enter a cycle?

The sequence decreases for the first time at n = 4.

PROG

(PARI) seq(start, terms) = my(x=start, i=1); print1(start, ", "); while(1, forprime(q=1, , if(Mod(q, x^2)^(x-1)==1, print1(q, ", "); x=q; i++; if(i >= terms, break({2}), break))))

seq(37, 20) \\ Print initial 20 terms of sequence

CROSSREFS

Row n = 12 of A249162.

Cf. A355597, A355598, A355599, A355601, A355602.

KEYWORD

allocated

nonn,hard,more

AUTHOR

Felix Fröhlich, Jul 09 2022

STATUS

approved

editing

#1 by Felix Fröhlich at Sat Jul 09 04:02:27 EDT 2022

NAME

allocated for Felix Fröhlich

KEYWORD

allocated

STATUS

approved