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A088056 a(1)= 3, a(n) = least prime obtained by prefixing the digits of a multiple of n to a(n-1). 2
3, 23, 1223, 81223, 2581223, 62581223, 1462581223, 1601462581223, 1081601462581223, 601081601462581223, 231601081601462581223, 36231601081601462581223, 7836231601081601462581223 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Digits of a(n) can be partitioned from (least siginifacnt one) right to left into multiples of 1 to n. a(6) = 62581223 ===> 6, 25, 8, 12, 2, 3.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..200

EXAMPLE

a(3) = 1223 and a(4) = 81223 is obtained by prefixing 8 to 1223.

MATHEMATICA

nxt[{n_, a_}]:=Module[{ida=IntegerDigits[a], k=1}, While[!PrimeQ[ FromDigits[ Join[ IntegerDigits[k(n+1)], ida]]], k++]; {n+1, FromDigits[ Join[ IntegerDigits[ k(n+1)], ida]]}]; Transpose[NestList[nxt, {1, 3}, 20]][[2]] (* Harvey P. Dale, Mar 26 2015 *)

CROSSREFS

Cf. A088057.

Sequence in context: A013393 A013390 A144986 * A009593 A009818 A210734

Adjacent sequences:  A088053 A088054 A088055 * A088057 A088058 A088059

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Sep 21 2003

EXTENSIONS

More terms from Sam Alexander, Feb 27 2004

STATUS

approved

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Last modified August 11 23:45 EDT 2020. Contains 336434 sequences. (Running on oeis4.)