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A090233 Puzzle-Box primes (lids). 1
11, 31, 71, 13, 41, 13, 17, 31, 13, 331, 761, 313, 751, 971, 919, 911, 661, 881, 211, 311, 571, 113, 541, 761, 313, 751, 521, 691, 661, 431, 421, 631, 619, 163, 331, 541, 317, 311, 281, 271, 491, 241, 211, 419, 137, 131, 127, 313, 281, 271, 251, 199, 191, 181 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Puzzle-box primes are intended to pique the interest of young school children in playing with numbers. The name is inspired by another Livermore resident, Harry L. Nelson, co-discover of M27 in 1979 and a maker of manipulative puzzles sometimes featured in the local press.

LINKS

Table of n, a(n) for n=0..53.

FORMULA

These are the lids for the base puzzle-box primes. When a base is prime, the lid is included in this sequences. Two primes form the box when the digits of the lid, placed over the base, line up to form the same number vertically. In the base prime, the largest digit is chosen, plus 1. All digits in the base prime are then subtracted from this number to form the lid.

EXAMPLE

a(1)=31. 13 is the base. When the prime lid, 31, is placed above the base 13, it forms a box: 31 over 13 and the two columns add to 4 and 4 [since 3 is the largest digit in the base, 3+1=4, all columns in base and lid must add to this number].

CROSSREFS

Cf. A090236.

Sequence in context: A174244 A136061 A296034 * A139836 A085715 A040973

Adjacent sequences:  A090230 A090231 A090232 * A090234 A090235 A090236

KEYWORD

easy,nonn

AUTHOR

Enoch Haga, Jan 23 2004

STATUS

approved

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Last modified June 12 14:20 EDT 2021. Contains 344956 sequences. (Running on oeis4.)