A069847 - OEIS

A069847

Number of distinct primes obtained by inserting a 6 at all possible places in n. This includes prefixing.

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

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OFFSET

1,13

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..20000

EXAMPLE

See the example in A069842.

MATHEMATICA

Table[ Count[ PrimeQ[ Union[ FromDigits /@ Table[ Insert[ IntegerDigits[n], 6, j], {j, 1, Floor[ Log[10, n] + 2]}]]], True], {n, 1, 105}]

PROG

(PARI) A069847(n) = { my(digs=digits(n), u=#digs, nums=Set([])); for(n=1, 1+u, nums = setunion(nums, [fromdigits(vector(1+u, i, if(i<n, digs[i], if(i>n, digs[i-1], 6))))])); #select(isprime, nums); }; \\ Antti Karttunen, Aug 23 2019

CROSSREFS

Cf. A069842, A069843, A069844, A069845, A069846, A069848, A069849, A069850 and A069851.

Sequence in context: A104194 A292261 A035153 * A238532 A097249 A112313

Adjacent sequences: A069844 A069845 A069846 * A069848 A069849 A069850

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Apr 16 2002

EXTENSIONS

Edited and extended by Robert G. Wilson v, Apr 18 2002

STATUS

approved