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A320229 Least semiprime from merging n consecutive semiprimes. 0
4, 46, 469, 25263334, 910141521, 469101415, 26333435383946, 3334353839464951, 91014152122252633, 65697477828586879193, 778285868791939495106111, 778285868791939495106111115118, 115118119121122123129133134141142143, 3538394649515557586265697477 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Apparently a(n) exists for any n.

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

n = 14: 35-38-39-46-49-51-55-57-58-62-65-69-74-77 => 1540961*2296225958681340790757,

n = 15: 87-91-93-94-95-106-111-115-118-119-121-122-123-129-133 => 53*165885650851058700285247530587209870361,

n = 16: 6-9-10-14-15-21-22-25-26-33-34-35-38-39-46-49 => 43669*15823906023088521224290421.

PROG

(Perl) use ntheory ":all"; sub ls { my($n, $k, $s)=(shift, 0, 0); do { $k++; $s = fromdigits(join "", map { nth_semiprime($_) } $k .. $k+$n-1); } until is_semiprime($s); $s; } print "$_ ", ls($_), "\n" for 1..30; # Dana Jacobsen, Oct 19 2018

CROSSREFS

Sequence in context: A132932 A231787 A173716 * A097952 A097643 A155652

Adjacent sequences:  A320226 A320227 A320228 * A320230 A320231 A320232

KEYWORD

nonn,base

AUTHOR

Zak Seidov, Oct 08 2018

STATUS

approved

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Last modified June 12 06:52 EDT 2021. Contains 344943 sequences. (Running on oeis4.)