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

1,1

Comments

"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.

Links

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

Crossrefs

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

Sequence in context: A215968 A064832 A129638 * A127624 A097616 A146150

Adjacent sequences: A333353 A333354 A333355 * A333357 A333358 A333359

Keyword

base,nonn

Author

Carole Dubois and Eric Angelini, Mar 15 2020

Status

approved