A391940 RSA numbers.

1522605027922533360535618378132637429718068114961380688657908494580122963258952897654000350692006139, 35794234179725868774991807832568455403003778024228226193532908190484670252364677411513516111204504060317568667, 227010481295437363334259960947493668895875336466084780038173258247009162675779735389791151574049166747880487470296548479

Offset

1,1

Comments

Sequence contains 45 semiprimes from the original 1991 RSA Factoring Challenge, and also eight from the 2001 extension of the challenge, and also includes as its fourth term RSA-129, which was not part of the 1991 challenge, but rather related to Martin Gardner's Mathematical Games column in the August 1977 issue of Scientific American. As no new challenges are forthcoming (The RSA Factoring Challenges ended in 2007), the sequence is finite and full, with 54 terms in total. The terms in the b-file are given in the ascending numerical order, regardless of the order they were published. The eight RSA numbers of the 2001 extension of the challenge occur at indices n=11 (RSA-576), n=14 (RSA-640), n=17 (RSA-704), n=21 (RSA-768), n=26 (RSA-896), n=31 (RSA-1024), n=48 (RSA-1536) and n=54 (RSA-2048).

When more factorizations of these terms will be attained, the b-files of sequences A391941 and A391942 should be respectively updated.

Links

Antti Karttunen, Table of n, a(n) for n = 1..54

Wikipedia, RSA Factoring Challenge.

Wikipedia, RSA numbers.

Formula

a(n) = A391941(n) * A391942(n).

Crossrefs

Subsequence of A046388.

Cf. A391941 (smaller prime factor), A391942 (greater prime factor), A391943 (binary widths of terms), A391944 (decimal digit counts), A391945 (decimal digit sums).

Sequence in context: A095588 A095590 A065004 * A095592 A095594 A095596

Adjacent sequences: A391937 A391938 A391939 * A391941 A391942 A391943

Keyword

nonn,fini,full

Author

Antti Karttunen, Dec 28 2025

Status

approved