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A076161
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Numbers n such that n + sum of squares of digits of n (A258881) is a prime.
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4
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1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 31, 34, 57, 73, 74, 75, 78, 91, 94, 97, 100, 101, 102, 103, 105, 107, 108, 109, 121, 122, 123, 126, 127, 128, 140, 142, 146, 148, 160, 161, 165, 166, 168, 182, 183, 188, 213, 216, 217, 234, 251, 275, 277, 297, 301
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OFFSET
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1,2
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LINKS
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EXAMPLE
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12 is a term because 12+(1^2+2^2) = 17 is a prime.
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MAPLE
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filter:= proc(n) local t; isprime(n+add(t^2, t=convert(n, base, 10))) end proc:
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PROG
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(Python)
from sympy import isprime
def ssd(n): return sum(int(d)**2 for d in str(n))
def ok(n): return isprime(n + ssd(n))
def aupto(limit): return [m for m in range(1, limit+1) if ok(m)]
(PARI) isok(n) = isprime(n + norml2(digits(n))); \\ Michel Marcus, Jan 31 2021
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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