A337845 - OEIS

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A337845

Primes with a digital sum that is less than the digital sum of the previous prime.

11, 23, 31, 41, 53, 61, 71, 83, 97, 101, 113, 131, 151, 163, 173, 181, 211, 233, 241, 263, 271, 281, 307, 311, 331, 353, 367, 373, 383, 397, 401, 421, 443, 457, 461, 487, 491, 503, 521, 563, 571, 593, 601, 613, 631, 653, 661, 683, 691, 701, 727, 733, 743, 751

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OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

11 has digital sum 2 which is less than the digital sum of the previous prime (7).

MATHEMATICA

s[n_] := Plus @@ IntegerDigits[n]; p = Select[Range[1000], PrimeQ]; p[[1 + Position[Differences[s /@ p], _?(# < 0 &)] // Flatten]] (* Amiram Eldar, Sep 26 2020 *)

Prime[#]&/@(Flatten[Position[Partition[Table[Total[IntegerDigits[Prime[n]]], {n, 200}], 2, 1], _?(#[[2]]<#[[1]]&), 1, Heads->False]]+1) (* Harvey P. Dale, Aug 05 2022 *)

PROG

(PARI) isok(p) = isprime(p) && (sumdigits(p) < sumdigits(precprime(p-1))); \\ Michel Marcus, Sep 26 2020

CROSSREFS

Cf. A007605.

Sequence in context: A060399 A030665 A077501 * A030675 A110786 A059642

Adjacent sequences: A337842 A337843 A337844 * A337846 A337847 A337848

KEYWORD

nonn,base

AUTHOR

Anthony Winkelspecht, Sep 25 2020

STATUS

approved