OFFSET
1,1
COMMENTS
RSA-2048 is A391940(54), and remains so far unfactored. - Antti Karttunen, Jan 01 2026
a(14) > 50000. - Michael S. Branicky, Jan 03 2026
EXAMPLE
(RSA-2048) - 10^107 is prime.
MATHEMATICA
Position[PrimeQ[Table[ \
251959084756578934940271832400483985714292821262040320277771378360436620207075\
955562640185258807844069182906412495150821892985591491761845028084891200728449\
926873928072877767359714183472702618963750149718246911650776133798590957000973\
304597488084284017974291006424586918171951187461215151726546322822168699875491\
824224336372590851418654620435767984233871847744479207399342365848238242811981\
638150106748104516603773060562016196762561338441436038339044149526344321901146\
575444541784240209246165157233507787077498171257724679629263863563732899121548\
31438167899885040445364023527381951378636564391212010397122822120720357 - \
10^n, {n, 1617}]], True]
PROG
(PARI) \\ Set N to RSA-2048, A391940(54).
for(n=1, 617, if(ispseudoprime(abs(N-10^n)), print1(n", ")))
CROSSREFS
KEYWORD
nonn,more,less
AUTHOR
Joao da Silva (zxawyh66(AT)yahoo.com), Jan 30 2006
EXTENSIONS
Added "abs" to definition so as to allow for more than just one term - Antti Karttunen, Jan 01 2026
a(6)-a(13) from Michael S. Branicky, Jan 02 2026
STATUS
approved