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A324262 a(n) is the smallest term of A324261 with 2n digits if it exists, otherwise 0. 2
0, 0, 0, 0, 13731373, 1190911909, 0, 19090911909091, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7316763215964848081373167632159648480813, 111272689909091345969111272689909091345969, 10527889691056689261011052788969105668926101, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

There can be a large number of terms in A324261 with 2n digits. For example, there are 227 terms with length 66. Selecting only the smallest term for each length allows terms to be listed for larger values of n.

The terms of A324261 with length 2n are formed by concatenating two copies of prime p, where p has length n and the decimal representation of p contains all the prime factors of 10^n + 1 as described in A324261 and A083359.

Subsequence of A020338 (Doublets: base-10 representation is the juxtaposition of two identical strings).

LINKS

Deron Stewart, Table of n, a(n) for n = 0..61

EXAMPLE

With m = 27 there are three prime p's: 114175966169705419295257913, 352579141759661697054192911 and 525791141759661697054192913. The smallest p concatenated with itself gives a(27) = 114175966169705419295257913114175966169705419295257913.

With m = 28 there are no solutions so a(28) = 0.

CROSSREFS

Cf. A083359, A020338, A324261, A324257.

Sequence in context: A251565 A082256 A324261 * A321364 A116148 A210085

Adjacent sequences:  A324259 A324260 A324261 * A324263 A324264 A324265

KEYWORD

nonn,base

AUTHOR

Deron Stewart, Mar 13 2019

STATUS

approved

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Last modified January 26 18:26 EST 2022. Contains 350599 sequences. (Running on oeis4.)