A081227 a(n) is the number of digits in common between n and the n-th prime in base 10.

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

Offset

1,73

Comments

Duplicate digits are ignored for comparison purposes; e.g. 1002 and 3050 only have one digit in common, 0.

Links

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

Example

a(7)=1 since the 7th prime is 17.

Maple

digcomp := proc(A, B) local a, b, crit, f; description "returns the digits that 'A' and 'B' have in common; if a third argument is given and it is 'sum' then the sum of the common digits is returned, else if it is 'num' then the number of common digits is returned."; if nargs>2 then crit := args[3] else crit := NULL fi; a := convert(`if`(A=0, [0], (convert(A, base, 10))), set); b := convert(`if`(B=0, [0], (convert(B, base, 10))), set); f := a intersect b; if crit=sum then return `if`(nops(f)>0, `+`(op(f)), -1) elif crit=num then return nops(f) else return f; fi; end proc;

Crossrefs

Cf. A081228, A081229.

Sequence in context: A092410 A100204 A073779 * A301469 A004610 A068934

Adjacent sequences: A081224 A081225 A081226 * A081228 A081229 A081230

Keyword

base,easy,nonn

Author

Francois Jooste (pin(AT)myway.com), Mar 11 2003

Status

approved