A210539 Positions n of digits "1" in the concatenated terms of A210538 for which A210538(n) is not prime.

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

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

Table of n, a(n) for n=1..56.

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

Cf. A210538.

Sequence in context: A061016 A038366 A375323 * A173231 A172055 A249648

Adjacent sequences: A210536 A210537 A210538 * A210540 A210541 A210542

Keyword

nonn,base

Author

M. F. Hasler, Mar 22 2012

Status

approved