A069604 - OEIS

A069604

a(1) = 1; for n>1, a(n) = smallest number with all odd digits giving a prime in concatenation with the previous terms.

1, 1, 3, 11, 1, 3, 3, 53, 13, 39, 9, 3, 399, 11, 9, 133, 3, 11, 51, 111, 13, 53, 31, 3, 173, 1, 317, 519, 579, 1, 573, 357, 5111, 39, 51, 73, 3317, 1977, 5173, 579, 357, 359, 9, 57, 3991, 959, 951, 7, 111, 1959, 39, 191, 3357, 3151, 3137, 577, 117, 1353, 951, 153, 99

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..61.

EXAMPLE

a(5) = 1 and the number 113111 is a prime.

MATHEMATICA

a[1] = 1; a[n_] := a[n] = Block[{k = 1, c = IntegerDigits @ Table[ a[i], {i, n - 1}]}, While[ Union[ Mod[ IntegerDigits[k], 2]] != {1} || !PrimeQ[ FromDigits[ Join[ Flatten[c], IntegerDigits[k]]]], k = k + 1]; k]; Table[ a[n], {n, 61}] (* corrected by Jason Yuen, Jun 22 2025 *)

CROSSREFS

Cf. A033680, A074336, A092528, A069602.

Sequence in context: A117526 A051498 A092528 * A354979 A098332 A096663

Adjacent sequences: A069601 A069602 A069603 * A069605 A069606 A069607

KEYWORD

nonn,base

AUTHOR

Amarnath Murthy, Mar 26 2002

EXTENSIONS

Corrected and extended by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

STATUS

approved