A069842 Number of distinct primes obtained by inserting a 1 at all possible places in n. This includes prefixing and suffixing.

1, 0, 2, 1, 0, 1, 2, 0, 1, 1, 0, 0, 2, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 2, 1, 0, 0, 2, 0, 2, 0, 0, 0, 2, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 3, 0, 1, 1, 0, 1, 0, 0, 2, 0, 0, 1, 0, 0, 3, 1, 0, 1, 2, 0, 2, 1, 0, 0, 1, 0, 1, 1, 0, 0, 2, 0, 2, 1, 0, 0, 0, 0, 0, 1, 0, 0, 2, 0, 1, 1, 0, 0, 2, 0, 3, 0, 0, 1, 3, 0, 1

Offset

1,3

Links

Table of n, a(n) for n=1..105.

Example

a(13) = 2 because 13 -> 113, 113, 131 -> 113 and 131 which are both prime.

Mathematica

Table[ Count[ PrimeQ[ Union[ FromDigits /@ Table[ Insert[ IntegerDigits[n], 1, j], {j, 1, Floor[ Log[10, n] + 2]}]]], True], {n, 1, 105}]

Crossrefs

Cf. A069843, A069844, A069845, A069846, A069847, A069848, A069849, A069850, A069851.

Sequence in context: A323989 A262988 A039999 * A083056 A356733 A321100

Adjacent sequences: A069839 A069840 A069841 * A069843 A069844 A069845

Keyword

base,nonn

Author

Amarnath Murthy, Apr 16 2002

Extensions

More terms from Vladeta Jovovic, Apr 17 2002

Edited by Robert G. Wilson v, Apr 18 2002

Status

approved