

A280915


Primes where difference between largest digit and all other digits is a positive square.


3



11, 23, 37, 43, 59, 67, 73, 89, 101, 113, 127, 131, 149, 157, 167, 179, 197, 211, 239, 241, 257, 263, 269, 271, 293, 307, 311, 337, 347, 359, 373, 419, 421, 431, 449, 461, 491, 509, 523, 541, 571, 593, 607, 617, 641, 719, 733, 743, 751, 761, 809, 853, 941, 953, 971, 1013, 1021, 1031
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OFFSET

1,1


COMMENTS

If the largest digit L (say) is repeated, the criterion is that that L  (sum of all digits except for one copy of L) is a square.


LINKS



EXAMPLE

Prime 1153 is in a(n) since 5311=0. Zero is square.
Prime 1163 is in a(n) since 6311=1. One is square.
Prime 1171 is in a(n) since 7111=4. Four is square.


MATHEMATICA

Select[Prime@ Range@ 175, IntegerQ@ Sqrt@ Fold[#1  #2 &, Max@ #, Rest@ #] &@ Reverse@ Sort@ IntegerDigits@ # &] (* Michael De Vlieger, Feb 02 2017 *)


PROG

(PARI) is(n)=my(d=digits(n)); issquare(2*vecmax(d)vecsum(d)) && isprime(n) \\ Charles R Greathouse IV, Feb 05 2017


CROSSREFS

This sequence is a parent sequence of A156753.


KEYWORD

nonn,base


AUTHOR



STATUS

approved



