A280915 Primes where difference between largest digit and all other digits is a positive square.

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

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

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Example

Prime 1153 is in a(n) since 5-3-1-1=0. Zero is square.
Prime 1163 is in a(n) since 6-3-1-1=1. One is square.
Prime 1171 is in a(n) since 7-1-1-1=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.

Sequence in context: A079664 A160268 A135978 * A139493 A275591 A250665

Adjacent sequences: A280912 A280913 A280914 * A280916 A280917 A280918

Keyword

nonn,base

Author

Osama Abuajamieh, Jan 10 2017

Status

approved