A333234 -id:A333234 - cp's OEIS frontend

A333356 Terms describing the nonprime digits' positions in the way explained in the Comments section.

11, 21, 41, 54, 61, 84, 96, 101, 118, 124, 139, 146, 151, 160, 171, 181, 191, 208, 211, 234, 241, 269, 271, 284, 296, 301, 321, 331, 346, 350, 361, 381, 391, 408, 411, 421, 439, 441, 460, 478, 491, 501, 534, 554, 561, 586, 599, 621, 648, 654, 679, 686, 700, 711, 741, 771, 794, 806, 830, 856, 861, 888

Offset: 1

Carole Dubois and Eric Angelini, Mar 15 2020

"11" must be read: "At position 1, there is a 1". And indeed, there is, when considering the sequence as a string of concatenated digits;
"21" reads: "At position 2, there is a 1" - which is true;
"41" reads: "At position 4, there is a 1" - which is also true;
"54" reads: "At position 5, there is a 4" - which is also true;
...
"101" reads: "At position 10, there is a 1" - which is true (the 1 in 61); etc.
We don't read the 2 of 21 as this 2 is a prime digit. Thus 32 and 75 are not in the sequence.

Carole Dubois, Table of n, a(n) for n = 1..2322

Cf. A333234 (nonprimes describing the nonprime digits' positions), A264646 (n concatenated with the n-th digit of S).

cp's OEIS Frontend

A333356 Terms describing the nonprime digits' positions in the way explained in the Comments section.

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