

A210539


Positions n of digits "1" in the concatenated terms of A210538 for which A210538(n) is not prime.


1



1, 10, 19, 22, 28, 34, 187, 197, 210, 220, 232, 247, 250, 253, 256, 262, 280, 286, 289, 307, 318, 321, 329, 332, 353, 358, 361, 364, 383, 413, 426, 445, 451, 453, 462, 472, 484, 490, 512, 523, 532, 538, 559, 572, 577, 579, 586, 597, 635, 644, 723, 809, 882, 930, 941, 1020
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OFFSET

1,2


COMMENTS

Primes > 7 occur in A210538 at indices n corresponding to digits "1" in the concatenation of the terms. This sequence lists counterexamples for which the converse is not true, i.e., position of digits "1" not corresponding to primes.
Note the irregular distribution: there are no terms between 34 and 187, but then many terms up to 597. These are followed by only 7 terms preceding 1020, which starts a series of 6 terms up to 1140.


LINKS



EXAMPLE

a(1)=1 because the 1st digit of A210538 is "1", but A210538(1)=1 is not prime.
a(2)=10, because the 10th digit of A210538 is "1", but A210538(10)=10 is not prime.


CROSSREFS



KEYWORD

nonn,base


AUTHOR



STATUS

approved



